Digital broadcasting system and method of processing data in the digital broadcasting system

ABSTRACT

A digital broadcasting system and a data processing method are disclosed. A receiving system of the digital broadcasting system includes a receiving unit, a demodulator, an equalizer, a block decoder, and a RS frame decoder. The receiving unit receives a broadcast signal including mobile service data and main service data. The mobile service data may configure a RS frame. The RS frame includes at least one data packet for the mobile service data, RS parity generated based on the at least one data packet, and CRC checksum generated based on the at least one data packet and the RS parity. The demodulator converts RS frame data included in the broadcast signal received by the receiving unit into a baseband RS frame data. The equalizer performs channel equalization on the data demodulated by the demodulator. The block decoder performs symbol-decoding on the data channel-equalized by the equalizer in block units. The RS frame decoder performs CRC-decoding and RS-decoding on the decoded mobile service data in RS frame units, thereby correcting errors occurred in the mobile service data within the RS frame.

This application claims the benefit of U.S. Provisional Application No.60/957,714, filed on Aug. 24, 2007, which is hereby incorporated byreference. Also, this application claims the priority benefit of KoreanApplication No. 10-2008-0083016, filed on Aug. 25, 2008, which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. The Field

The present invention relates to a digital broadcasting system and amethod of processing data in a digital broadcasting system fortransmitting and receiving digital broadcast signals.

2. Description of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the digital broadcast receiving system may bedeteriorated in a poor channel environment. Particularly, sinceresistance to changes in channels and noise is more highly required whenusing portable and/or mobile broadcast receivers, the receivingperformance may be even more deteriorated when transmitting mobileservice data by the VSB transmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is to provide a digital broadcastingsystem and a data processing method that are highly resistant to channelchanges and noise.

The present invention is to provide a digital broadcasting system and adata processing method that can enhance the receiving performance of thereceiving system by performing additional encoding on mobile servicedata and by transmitting the processed data to the receiving system.

The present invention is to provide a digital broadcasting system and adata processing method that can also enhance the receiving performanceof the receiving system by inserting known data already known inaccordance with a pre-agreement between the receiving system and thetransmitting system in a predetermined region within a data region.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital broadcast transmitting system may include a service multiplexerand a transmitter. The service multiplexer may multiplex mobile servicedata and main service data at a predetermined coding rate and maytransmit the multiplexed data to the transmitter. The transmitter mayperform additional encoding on the mobile service data being transmittedfrom the service multiplexer. The transmitter may also group a pluralityof additionally encoded mobile service data packets so as to form a datagroup. The transmitter may multiplex mobile service data packetsincluding mobile service data and main service data packets includingmain service data in packet units and may transmit the multiplexed datapackets to a digital broadcast receiving system.

Herein, the data group may be divided into a plurality of regionsdepending upon a degree of interference of the main service data. Also,a long known data sequence may be periodically inserted in regionswithout interference of the main service data.

Also, a digital broadcast receiving system according to an embodiment ofthe present invention may be used for modulating and channel equalizingthe known data sequence.

In another aspect of the present invention, a receiving system includesa receiving unit, a demodulator, an equalizer, a block decoder, and a RSframe decoder. The receiving unit receives a broadcast signal includingmobile service data and main service data. The mobile service data mayconfigure a RS frame. The RS frame includes at least one data packet forthe mobile service data, RS parity generated based on the at least onedata packet, and CRC checksum generated based on the at least one datapacket and the RS parity. The demodulator converts RS frame dataincluded in the broadcast signal received by the receiving unit into abaseband RS frame data. The equalizer performs channel equalization onthe data demodulated by the demodulator. The block decoder performssymbol-decoding on the data channel-equalized by the equalizer in blockunits. The RS frame decoder performs CRC-decoding and RS-decoding on thedecoded mobile service data in RS frame units, thereby correcting errorsoccurred in the mobile service data within the RS frame.

A data group configures a RS frame, N number of known data sequences areinserted in some regions among a plurality of regions within the datagroup, and a transmission parameter is inserted between a first knowndata sequence and a second known data sequence, among the N number ofknown data sequences.

The receiving system may include a transmission parameter detector fordetecting the transmission parameter, and a power controller forcontrolling power based upon the detected transmission parameter,thereby receiving a slot which a data group including requested mobileservice data is assigned.

The receiving system may include a known sequence detector for detectingthe known data, the equalizer channel-equalizes the mobile service datausing the detected known data.

In the receiving system, one RS frame data may be assigned to at leastsome regions among a plurality of data group, the data group configuringa plurality of regions, and then the assigned RS frame data is received.

In the receiving system, one RS frame data among a plurality of RS framemay be assigned to some regions among a plurality of data group, thedata group configuring a plurality of regions, and the other RS framedata may be assigned to the remaining regions within the correspondingdata group, and then the assigned RS frame data is received.

In another aspect of the present invention, a method for processing datain a receiving system includes the steps of receiving a broadcast signalincluding mobile service data and main service data, the mobile servicedata configuring a RS frame, the RS frame including at least one datapacket for the mobile service data, RS parity generated based on the atleast one data packet, and CRC checksum generated based on the at leastone data packet and the RS parity, converting RS frame data included inthe received broadcast signal into a baseband RS frame data, performingchannel equalization on the demodulated data, performing symbol-decodingon the channel-equalized data in block units, and performingCRC-decoding and RS-decoding on the decoded mobile service data in RSframe units, thereby correcting errors occurred in the mobile servicedata within the RS frame.

The objectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription hereof as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of a MPH frame for transmitting andreceiving mobile service data according to the present invention;

FIG. 2 illustrates an exemplary structure of a VSB frame;

FIG. 3 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention;

FIG. 4 illustrates a block diagram showing an example of a servicemultiplexer;

FIG. 5 illustrates a block diagram showing an example of a transmitteraccording to an embodiment of the present invention;

FIG. 6 illustrates a block diagram showing an example of a pre-processoraccording to the present invention;

FIG. 7 illustrates RS encoding processes according to an embodiment ofthe present invention;

FIG. 8 illustrates an example of performing a row permutation (orinterleaving) process in super frame units according to the presentinvention;

FIG. 9A and FIG. 9B illustrate examples of RS frames according to thepresent invention;

FIG. 10A illustrates a structure of data group after being datainterleaved according to the present invention;

FIG. 10B illustrates a structure of data group before being datainterleaved according to the present invention;

FIG. 11 illustrates an exemplary process of dividing an RS frame forconfiguring a data group according to the present invention;

FIG. 12 illustrates a mapping example of the positions to which thefirst 4 slots of a sub-frame are assigned with respect to a VSB frameaccording to the present invention;

FIG. 13 illustrates an example of data groups of a single ensemble beingassigned (or allocated) to an MPH frame;

FIG. 14 illustrates an example of data groups of two ensembles beingassigned (or allocated) to an MPH frame;

FIG. 15 illustrates an example of data groups of three ensembles beingassigned (or allocated) to an MPH frame;

FIG. 16A to FIG. 16C illustrate examples of signaling informationaccording to the present invention;

FIG. 17 illustrates an example of power saving of in a receiver in aslot unit according to the present invention;

FIG. 18 illustrates examples of MPH-related information according to thepresent invention;

FIG. 19( a) to FIG. 19( e) illustrate an example of signalinginformation scenario being transmitted in signaling information regionaccording to the present invention;

FIG. 20 illustrates a block diagram of a block processor according to anembodiment of the present invention;

FIG. 21A to FIG. 21C illustrate block views showing exemplary operationsof the symbol encoder having the coding rate of ¼ according to anembodiment of the present invention;

FIG. 22A illustrates a detailed block diagram of a ½ outer encoderaccording to an embodiment of the present invention;

FIG. 22B illustrates a detailed block diagram of a ¼ outer encoderaccording to an embodiment of the present invention;

FIG. 23( a) to FIG. 23( c) illustrate a variable length interleavingprocess of a symbol interleaver according to an embodiment of thepresent invention;

FIG. 24A and FIG. 24B illustrate a block diagram showing a structure ofa block processor according to another embodiment of the presentinvention;

FIG. 25( a) to FIG. 25( c) illustrate examples of block-encoding andtrellis-encoding processes according to an embodiment of the presentinvention;

FIG. 26 illustrates a block diagram of a trellis encoding moduleaccording to an embodiment of present invention;

FIG. 27A and FIG. 27B illustrate a concatenation between a blockprocessor and a trellis encoding module according to the presentinvention;

FIG. 28 illustrates a block diagram showing a structure of a blockprocessor according to another embodiment of the present invention;

FIG. 29 illustrates a block diagram of a demodulating unit of areceiving system according to an embodiment of the present invention;

FIG. 30 illustrates a data structure showing an example of known databeing periodically inserted in valid data according to the presentinvention;

FIG. 31 illustrates a block diagram of a demodulator according to anembodiment of the present invention;

FIG. 32 illustrates a detailed block diagram of the demodulator;

FIG. 33 illustrates a block diagram of a frequency offset estimatoraccording to an embodiment of the present invention;

FIG. 34 illustrates a block diagram of a known data detector and initialfrequency offset estimator according to the present invention;

FIG. 35 illustrates a block diagram of a partial correlator shown inFIG. 34;

FIG. 36 illustrates an example of the timing recovery unit according tothe present invention;

FIG. 37( a) and FIG. 37( b) illustrate examples of detecting timingerror in a time domain;

FIG. 38( a) and FIG. 38( b) illustrate other examples of detectingtiming error in a time domain;

FIG. 39 illustrates an example of detecting timing error usingcorrelation values of FIG. 37 and FIG. 38;

FIG. 40 illustrates an example of a timing error detector for detectingtiming error in a time domain according to the present invention;

FIG. 41 illustrates an example of a timing error detector for detectingtiming frequency error according to the present invention;

FIG. 42 illustrates another example of a timing error detector fordetecting timing frequency error according to the present invention;

FIG. 43 illustrates a block diagram of a DC remover according to anembodiment of the present invention;

FIG. 44 illustrates an example of shifting sample data inputted to a DCestimator shown in FIG. 43;

FIG. 45 illustrates a block diagram of a DC remover according to anotherembodiment of the present invention;

FIG. 46 illustrates a block diagram of an example of a channel equalizeraccording to the present invention;

FIG. 47 illustrates a detailed block diagram of an example of aremaining carrier phase error estimator shown in FIG. 46;

FIG. 48 illustrates a block diagram of an example of a phase errordetector shown in FIG. 47;

FIG. 49 illustrates a block diagram of an example of a phase compensatorshown in FIG. 47;

FIG. 50 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 51 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 52 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 53 illustrates a block diagram of an example of a CIR estimatoraccording to the present invention;

FIG. 54 illustrates a block diagram of an example of a block decoderaccording to the present invention;

FIG. 55 illustrates a block diagram of an example of a feedbackdeformatter shown in FIG. 54;

FIG. 56 and FIG. 57 illustrate process steps of error correctiondecoding according to an embodiment of the present invention;

FIG. 58 illustrates a block diagram of a receiving system according toan embodiment of the present invention;

FIG. 59 illustrates a bit stream syntax for a VCT according to thepresent invention;

FIG. 60 illustrates a service_type field according to an embodiment ofthe present invention;

FIG. 61 illustrates a service location descriptor according to anembodiment of the present invention;

FIG. 62 illustrates examples that may be assigned to the stream_typefield according to the present invention;

FIG. 63 illustrates a bit stream syntax for an EIT according to thepresent invention; and

FIG. 64 illustrates a block diagram of a receiving system according toanother embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Hereinafter, the preferred embodiment of the present inventionwill be described with reference to the accompanying drawings. At thistime, it is to be understood that the following detailed description ofthe present invention illustrated in the drawings and described withreference to the drawings are exemplary and explanatory and technicalspirits of the present invention and main features and operation of thepresent invention will not be limited by the following detaileddescription.

Definition of the Terms Used in the Present Invention

Although general terms, which are widely used considering functions inthe present invention, have been selected in the present invention, theymay be changed depending on intention of those skilled in the art,practices, or new technology. Also, in specific case, the applicant mayoptionally select the terms. In this case, the meaning of the terms willbe described in detail in the description part of the invention.Therefore, it is to be understood that the terms should be defined basedupon their meaning not their simple title and the whole description ofthe present invention.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system. Additionally,among the terms used in the present invention, “MPH” corresponds to theinitials of “mobile”, “pedestrian”, and “handheld” and represents theopposite concept of a fixed-type system. Furthermore, the MPH servicedata may include at least one of mobile service data, pedestrian servicedata, and handheld service data, and will also be referred to as “mobileservice data” for simplicity. Herein, the mobile service data not onlycorrespond to MPH service data but may also include any type of servicedata with mobile or portable characteristics. Therefore, the mobileservice data according to the present invention are not limited only tothe MPH service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be transmitted as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls andsurveys, interactive education broadcast programs, gaming services,services providing information on synopsis, character, background music,and filming sites of soap operas or series, services providinginformation on past match scores and player profiles and achievements,and services providing information on product information and programsclassified by service, medium, time, and theme enabling purchase ordersto be processed. Herein, the present invention is not limited only tothe services mentioned above. In the present invention, the transmittingsystem provides backward compatibility in the main service data so as tobe received by the conventional receiving system. Herein, the mainservice data and the mobile service data are multiplexed to the samephysical channel and then transmitted.

Furthermore, the digital broadcast transmitting system according to thepresent invention performs additional encoding on the mobile servicedata and inserts the data already known by the receiving system andtransmitting system (e.g., known data), thereby transmitting theprocessed data. Therefore, when using the transmitting system accordingto the present invention, the receiving system may receive the mobileservice data during a mobile state and may also receive the mobileservice data with stability despite various distortion and noiseoccurring within the channel.

MPH Frame Structure

In the embodiment of the present invention, the mobile service data aremodulated in a VSB mode and transmitted to the receiving system. At thispoint, the transmitter groups a plurality of mobile service data packetsto form a RS frame so as to perform an encoding process for errorcorrection. Then, data included in the error correction encoded RS frameare allocated to a plurality of data groups. Subsequently, the pluralityof data groups are multiplexed with the main service data within an MPHframe, thereby transmitted to the receiving system. In the embodiment ofthe present invention, a plurality of data groups to which the dataincluded in the error correction encoded RS frame are allocatedconfigures an ensemble. More specifically, the data groups within anensemble share the same ensemble identification (ID). At this point,since a plurality of mobile services may be included in one RS frame, aplurality of mobile services may also be included in one ensemble. Eachmobile service within an ensemble (or RS frame) may be referred to avirtual channel.

A method of allocating the data groups included in an ensemble within asingle MPH frame will be described in detail in a later process. At thispoint, one MPH frame consists of K1 number of sub-frames, wherein onesub-frame includes K2 number of VSB frames. Each VSB frame consists ofK3 number of slots. In the embodiment of the present invention, K1 willbe set to 5, K2 will be set to 4, and K3 will be set to 4 (i.e., K1=5,K2=4, and K3=4). The values for K1, K2, and K3 presented in thisembodiment either correspond to values according to a preferredembodiment or are merely exemplary. Therefore, the above-mentionedvalues will not limit the scope of the present invention.

FIG. 1 illustrates a structure of a MPH frame for transmitting andreceiving mobile service data according to the present invention. In theexample shown in FIG. 1, one MPH frame consists of 5 sub-frame, whereineach sub-frame includes 4 VSB frames, and wherein each VSB frameincludes 4 slots. In this case, the MPH frame according to the presentinvention includes 5 sub-frames, 20 VSB frames, and 80 slots.

FIG. 2 illustrates an exemplary structure of a VSB frame, wherein oneVSB frame consists of 2 fields (i.e., an odd field and an even field).Herein, each field includes a field synchronization segment and 312 datasegments. More specifically, 2 slots are grouped to form one field, and2 slots are grouped to form one VSB frame. Therefore, one slot includes156 data segments (or packets).

General Description of the Transmitting System

FIG. 3 illustrates a block view showing a general structure of a digitalbroadcast transmitting system according to an embodiment of the presentinvention. Herein, the digital broadcast transmitting includes a servicemultiplexer 100 and a transmitter 200. Herein, the service multiplexer100 is located in the studio of each broadcast station, and thetransmitter 200 is located in a site placed at a predetermined distancefrom the studio. The transmitter 200 may be located in a plurality ofdifferent locations. Also, for example, the plurality of transmittersmay share the same frequency. And, in this case, the plurality oftransmitters receives the same signal. Accordingly, in the receivingsystem, a channel equalizer may compensate signal distortion, which iscaused by a reflected wave, so as to recover the original signal. Inanother example, the plurality of transmitters may have differentfrequencies with respect to the same channel.

A variety of methods may be used for data communication each of thetransmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of the8VSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSBmode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional encoding isperformed on the mobile service data. Thereafter, the additionallyencoded mobile service data are multiplexed with the main service datato a TS packet form, which is then transmitted. At this point, the datarate of the multiplexed TS packet is approximately 19.39 Mbps.

At this point, the service multiplexer 100 receives at least one type ofmobile service data and program specific information/program and systeminformation protocol (PSI/PSIP) table data for each mobile service so asto encapsulate the received data to each TS packet. Also, the servicemultiplexer 100 receives at least one type of main service data andPSI/PSIP table data for each main service and encapsulates the receiveddata to a transport stream (TS) packet. Subsequently, the TS packets aremultiplexed according to a predetermined multiplexing rule and outputsthe multiplexed packets to the transmitter 200.

Service Multiplexer

FIG. 4 illustrates a block view showing an example of the servicemultiplexer. The service multiplexer includes a controller 110 forcontrolling the overall operations of the service multiplexer, aPSI/PSIP generator 120 for the main service, a PSI/PSIP generator 130for the mobile service, a null packet generator 140, a mobile servicemultiplexer 150, and a transport multiplexer 160. The transportmultiplexer 160 may include a main service multiplexer 161 and atransport stream (TS) packet multiplexer 162. Referring to FIG. 4, atleast one type of compression encoded main service data and the PSI/PSIPtable data generated from the PSI/PSIP generator 120 for the mainservice are inputted to the main service multiplexer 161 of thetransport multiplexer 160. The main service multiplexer 161 encapsulateseach of the inputted main service data and PSI/PSIP table data to MPEG-2TS packet forms. Then, the MPEG-2 TS packets are multiplexed andoutputted to the TS packet multiplexer 162. Herein, the data packetbeing outputted from the main service multiplexer 161 will be referredto as a main service data packet for simplicity.

Thereafter, at least one type of the compression encoded mobile servicedata and the PSI/PSIP table data generated from the PSI/PSIP generator130 for the mobile service are inputted to the mobile servicemultiplexer 150. The mobile service multiplexer 150 encapsulates each ofthe inputted mobile service data and PSI/PSIP table data to MPEG-2 TSpacket forms. Then, the MPEG-2 TS packets are multiplexed and outputtedto the TS packet multiplexer 162. Herein, the data packet beingoutputted from the mobile service multiplexer 150 will be referred to asa mobile service data packet for simplicity. At this point, thetransmitter 200 requires identification information in order to identifyand process the main service data packet and the mobile service datapacket. Herein, the identification information may use valuespre-decided in accordance with an agreement between the transmittingsystem and the receiving system, or may be configured of a separate setof data, or may modify predetermined location value with in thecorresponding data packet. As an example of the present invention, adifferent packet identifier (PID) may be assigned to identify each ofthe main service data packet and the mobile service data packet.

In another example, by modifying a synchronization data byte within aheader of the mobile service data, the service data packet may beidentified by using the synchronization data byte value of thecorresponding service data packet. For example, the synchronization byteof the main service data packet directly outputs the value decided bythe ISO/IEC13818-1 standard (i.e., 0x47) without any modification. Thesynchronization byte of the mobile service data packet modifies andoutputs the value, thereby identifying the main service data packet andthe mobile service data packet. Conversely, the synchronization byte ofthe main service data packet is modified and outputted, whereas thesynchronization byte of the mobile service data packet is directlyoutputted without being modified, thereby enabling the main service datapacket and the mobile service data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, or only a portion of the synchronization byte may beinversed. As described above, any type of identification information maybe used to identify the main service data packet and the mobile servicedata packet. Therefore, the scope of the present invention is notlimited only to the example set forth in the description of the presentinvention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39-K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification. Herein, thetransport multiplexer 160 multiplexes the main service data packet beingoutputted from the main service multiplexer 161 and the mobile servicedata packet being outputted from the mobile service multiplexer 150.Thereafter, the transport multiplexer 160 transmits the multiplexed datapackets to the transmitter 200.

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. In this case, the mobileservice multiplexer 150 multiplexes and outputs null data packetsgenerated from the null packet generator 140 so that the output datarate can reach K Mbps. More specifically, in order to match the outputdata rate of the mobile service multiplexer 150 to a constant data rate,the null packet generator 140 generates null data packets, which arethen outputted to the mobile service multiplexer 150. For example, whenthe service multiplexer 100 assigns K Mbps of the 19.39 Mbps to themobile service data, and when the remaining (19.39-K) Mbps is,therefore, assigned to the main service data, the data rate of themobile service data that are multiplexed by the service multiplexer 100actually becomes lower than K Mbps. This is because, in case of themobile service data, the pre-processor of the transmitting systemperforms additional encoding, thereby increasing the amount of data.Eventually, the data rate of the mobile service data, which may betransmitted from the service multiplexer 100, becomes smaller than KMbps.

For example, since the pre-processor of the transmitter performs anencoding process on the mobile service data at a coding rate of at least½, the amount of the data outputted from the pre-processor is increasedto more than twice the amount of the data initially inputted to thepre-processor. Therefore, the sum of the data rate of the main servicedata and the data rate of the mobile service data, both beingmultiplexed by the service multiplexer 100, becomes either equal to orsmaller than 19.39 Mbps. Therefore, in order to match the data rate ofthe data that are finally outputted from the service multiplexer 100 toa constant data rate (e.g., 19.39 Mbps), an amount of null data packetscorresponding to the amount of lacking data rate is generated from thenull packet generator 140 and outputted to the mobile servicemultiplexer 150.

Accordingly, the mobile service multiplexer 150 encapsulates each of themobile service data and the PSI/PSIP table data that are being inputtedto a MPEG-2 TS packet form. Then, the above-described TS packets aremultiplexed with the null data packets and, then, outputted to the TSpacket multiplexer 162. Thereafter, the TS packet multiplexer 162multiplexes the main service data packet being outputted from the mainservice multiplexer 161 and the mobile service data packet beingoutputted from the mobile service multiplexer 150 and transmits themultiplexed data packets to the transmitter 200 at a data rate of 19.39Mbps.

According to an embodiment of the present invention, the mobile servicemultiplexer 150 receives the null data packets. However, this is merelyexemplary and does not limit the scope of the present invention. Inother words, according to another embodiment of the present invention,the TS packet multiplexer 162 may receive the null data packets, so asto match the data rate of the finally outputted data to a constant datarate. Herein, the output path and multiplexing rule of the null datapacket is controlled by the controller 110. The controller 110 controlsthe multiplexing processed performed by the mobile service multiplexer150, the main service multiplexer 161 of the transport multiplexer 160,and the TS packet multiplexer 162, and also controls the null datapacket generation of the null packet generator 140. At this point, thetransmitter 200 discards the null data packets transmitted from theservice multiplexer 100 instead of transmitting the null data packets.

Further, in order to allow the transmitter 200 to discard the null datapackets transmitted from the service multiplexer 100 instead oftransmitting them, identification information for identifying the nulldata packet is required. Herein, the identification information may usevalues pre-decided in accordance with an agreement between thetransmitting system and the receiving system. For example, the value ofthe synchronization byte within the header of the null data packet maybe modified so as to be used as the identification information.Alternatively, a transport_error_indicator flag may also be used as theidentification information.

In the description of the present invention, an example of using thetransport_error_indicator flag as the identification information will begiven to describe an embodiment of the present invention. In this case,the transport_error_indicator flag of the null data packet is set to‘1’, and the transport_error_indicator flag of the remaining datapackets are reset to ‘0’, so as to identify the null data packet. Morespecifically, when the null packet generator 140 generates the null datapackets, if the transport_error_indicator flag from the header field ofthe null data packet is set to ‘1’ and then transmitted, the null datapacket may be identified and, therefore, be discarded. In the presentinvention, any type of identification information for identifying thenull data packets may be used. Therefore, the scope of the presentinvention is not limited only to the examples set forth in thedescription of the present invention.

According to another embodiment of the present invention, a transmissionparameter may be included in at least a portion of the null data packet,or at least one table or an operations and maintenance (OM) packet (orOMP) of the PSI/PSIP table for the mobile service. In this case, thetransmitter 200 extracts the transmission parameter and outputs theextracted transmission parameter to the corresponding block and alsotransmits the extracted parameter to the receiving system if required.More specifically, a packet referred to as an OMP is defined for thepurpose of operating and managing the transmitting system. For example,the OMP is configured in accordance with the MPEG-2 TS packet format,and the corresponding PID is given the value of 0x1FFA. The OMP isconfigured of a 4-byte header and a 184-byte payload. Herein, among the184 bytes, the first byte corresponds to an OM_type field, whichindicates the type of the OM packet.

In the present invention, the transmission parameter may be transmittedin the form of an OMP. And, in this case, among the values of thereserved fields within the OM_type field, a pre-arranged value is used,thereby indicating that the transmission parameter is being transmittedto the transmitter 200 in the form of an OMP. More specifically, thetransmitter 200 may find (or identify) the OMP by referring to the PID.Also, by parsing the OM_type field within the OMP, the transmitter 200can verify whether a transmission parameter is included after theOM_type field of the corresponding packet. The transmission parametercorresponds to supplemental data required for processing mobile servicedata from the transmitting system and the receiving system.

Herein, the transmission parameter may include data group information,region information within the data group, RS frame information, superframe information, MPH frame information, ensemble information,information associated with serial concatenated convolution code (SCCC),and RS code information. The transmission parameter may also includeinformation on how signals of a symbol domain are encoded in order totransmit the mobile service data, and multiplexing information on howthe main service data and the mobile service data or various types ofmobile service data are multiplexed. The information included in thetransmission parameter are merely exemplary to facilitate theunderstanding of the present invention.

And, the adding and deleting of the information included in thetransmission parameter may be easily modified and changed by anyoneskilled in the art. Therefore, the present invention is not limited tothe examples proposed in the description set forth herein.

Furthermore, the transmission parameters may be provided from theservice multiplexer 100 to the transmitter 200. Alternatively, thetransmission parameters may also be set up by an internal controller(not shown) within the transmitter 200 or received from an externalsource.

Transmitter

FIG. 5 illustrates a block view showing an example of the transmitter200 according to an embodiment of the present invention. Herein, thetransmitter 200 includes a demultiplexer 210, a packet jitter mitigator220, a pre-processor 230, a packet multiplexer 240, a post-processor250, a synchronization (sync) multiplexer 260, and a transmission unit270. Herein, when a data packet is received from the service multiplexer100, the demultiplexer 210 should identify whether the received datapacket corresponds to a main service data packet, a mobile service datapacket, or a null data packet. For example, the demultiplexer 210 usesthe PID within the received data packet so as to identify the mainservice data packet and the mobile service data packet. Then, thedemultiplexer 210 uses a transport_error_indicator field to identify thenull data packet. The main service data packet identified by thedemultiplexer 210 is outputted to the packet jitter mitigator 220, themobile service data packet is outputted to the pre-processor 230, andthe null data packet is discarded. If a transmission parameter isincluded in the null data packet, then the transmission parameter isfirst extracted and outputted to the corresponding block. Thereafter,the null data packet is discarded.

The pre-processor 230 performs an additional encoding process of themobile service data included in the service data packet, which isdemultiplexed and outputted from the demultiplexer 210. Thepre-processor 230 also performs a process of configuring a data group sothat the data group may be positioned at a specific place in accordancewith the purpose of the data, which are to be transmitted on atransmission frame. This is to enable the mobile service data to respondswiftly and strongly against noise and channel changes. Thepre-processor 230 may also refer to the transmission parameter whenperforming the additional encoding process. Also, the pre-processor 230groups a plurality of mobile service data packets to configure a datagroup. Thereafter, known data, mobile service data, RS parity data, andMPEG header are allocated to pre-determined regions within the datagroup.

Pre-Processor within Transmitter

FIG. 6 illustrates a block view showing an example of the pre-processor230 according to the present invention. The pre-processor 230 includes adata randomizer 301, a RS frame encoder 302, a block processor 303, agroup formatter 304, a data deinterleaver 305, a packet formatter 306.The data randomizer 301 within the above-described pre-processor 230randomizes the mobile service data packet including the mobile servicedata that is inputted through the demultiplexer 210. Then, the datarandomizer 301 outputs the randomized mobile service data packet to theRS frame encoder 302. At this point, since the data randomizer 301performs the randomizing process on the mobile service data, therandomizing process that is to be performed by the data randomizer 251of the post-processor 250 on the mobile service data may be omitted. Thedata randomizer 301 may also discard the synchronization byte within themobile service data packet and perform the randomizing process. This isan option that may be chosen by the system designer. In the examplegiven in the present invention, the randomizing process is performedwithout discarding the synchronization byte within the mobile servicedata packet.

The RS frame encoder 302 groups a plurality of mobile thesynchronization byte within the mobile service data packets that israndomized and inputted, so as to create a RS frame. Then, the RS frameencoder 302 performs at least one of an error correction encodingprocess and an error detection encoding process in RS frame units.Accordingly, robustness may be provided to the mobile service data,thereby scattering group error that may occur during changes in afrequency environment, thereby enabling the mobile service data torespond to the frequency environment, which is extremely vulnerable andliable to frequent changes. Also, the RS frame encoder 302 groups aplurality of RS frame so as to create a super frame, thereby performinga row permutation process in super frame units. The row permutationprocess may also be referred to as a row interleaving process.Hereinafter, the process will be referred to as row permutation forsimplicity.

More specifically, when the RS frame encoder 302 performs the process ofpermuting each row of the super frame in accordance with apre-determined rule, the position of the rows within the super framebefore and after the row permutation process is changed. If the rowpermutation process is performed by super frame units, and even thoughthe section having a plurality of errors occurring therein becomes verylong, and even though the number of errors included in the RS frame,which is to be decoded, exceeds the extent of being able to becorrected, the errors become dispersed within the entire super frame.Thus, the decoding ability is even more enhanced as compared to a singleRS frame.

At this point, as an example of the present invention, RS-encoding isapplied for the error correction encoding process, and a cyclicredundancy check (CRC) encoding is applied for the error detectionprocess in the RS frame encoder 302. When performing the RS-encoding,parity data that are used for the error correction are generated. And,when performing the CRC encoding, CRC data that are used for the errordetection are generated. The RS encoding is one of forward errorcorrection (FEC) methods. The FEC corresponds to a technique forcompensating errors that occur during the transmission process. The CRCdata generated by CRC encoding may be used for indicating whether or notthe mobile service data have been damaged by the errors while beingtransmitted through the channel. In the present invention, a variety oferror detection coding methods other than the CRC encoding method may beused, or the error correction coding method may be used to enhance theoverall error correction ability of the receiving system. Herein, the RSframe encoder 302 refers to a pre-determined transmission parameterand/or the transmission parameter provided from the service multiplexer100 so as to perform operations including RS frame configuration, RSencoding, CRC encoding, super frame configuration, and row permutationin super frame units.

RS Frame Encoder within Pre-Processor

FIG. 7( a) to FIG. 7( e) illustrate error correction encoding and errordetection encoding processes according to an embodiment of the presentinvention. Particularly, when a data group is divided into regions A, B,C, and D, FIG. 7( a) to FIG. 7( e) respectively illustrate examples ofcreating RS frames, so that data that are to be allocated to regions A,B, C, and D are included in each RS frame, and of performing errorcorrection encoding and error detection encoding thereto.

More specifically, the RS frame encoder 302 first divides the inputtedmobile service data bytes to units of a predetermined length. Thepredetermined length is decided by the system designer. And, in theexample of the present invention, the predetermined length is equal to187 bytes, and, therefore, the 187-byte unit will be referred to as apacket for simplicity. For example, when the mobile service data thatare being inputted, as shown in FIG. 7( a), correspond to a MPEGtransport packet stream configured of 188-byte units, the firstsynchronization byte is removed, as shown in FIG. 7( b), so as toconfigure a 187-byte unit. Herein, the synchronization byte is removedbecause each mobile service data packet has the same value.

Meanwhile, when the input data of the RS frame do not correspond to theMPEG TS packet format, the data are read in 187-byte units withoutincluding the process of removing the MPEG synchronization byte, therebycreating a RS frame as shown in FIG. 7( c). More specifically, theprocess shown in FIG. 7( a) is omitted. In addition, when the input dataformat of the RS frame supports both the input data corresponding to theMPEG TS packet and the input data not corresponding to the MPEG TSpacket, such information may be included in a transmission parametertransmitted from the service multiplexer 100, thereby being sent to thetransmitter 200. Accordingly, the RS frame encoder 302 of thetransmitter 200 receives this information to be able to control whetheror not to perform the process of removing the MPEG synchronization byte(i.e., the process shown in FIG. 7( a)). Also, the transmitter providessuch information to the receiving system so as to control the process ofinserting the MPEG synchronization byte that is to be performed by theRS frame decoder of the receiving system.

Herein, the process of removing the synchronization byte may beperformed during a randomizing process of the data randomizer 301 in anearlier process. In this case, the process of the removing thesynchronization byte by the RS frame encoder 302 may be omitted.Moreover, when adding synchronization bytes from the receiving system,the process may be performed by the data derandomizer instead of the RSframe decoder. Therefore, if a removable fixed byte (e.g.,synchronization byte) does not exist within the mobile service datapacket that is being inputted to the RS frame encoder 302, or if themobile service data that are being inputted are not configured in apacket format, the mobile service data that are being inputted aredivided into 187-byte units, thereby configuring a packet for each187-byte unit.

Subsequently, as shown in FIG. 7( c), N number of packets configured of187 bytes is grouped to configure a RS frame. At this point, the RSframe is configured as a RS frame having the size of N(row)*187(column)bytes, in which 187-byte packets are sequentially inputted in a rowdirection. In order to simplify the description of the presentinvention, the RS frame configured as described above will also bereferred to as a first RS frame. More specifically, only pure mobileservice data are included in the first RS frame, which is the same asthe structure configured of 187 N-byte rows. Thereafter, the mobileservice data within the RS frame are divided into an equal size. Then,when the divided mobile service data are transmitted in the same orderas the input order for configuring the RS frame, and when one or moreerrors have occurred at a particular point during thetransmitting/receiving process, the errors are clustered (or gathered)within the RS frame as well. In this case, the receiving system uses aRS erasure decoding method when performing error correction decoding,thereby enhancing the error correction ability. At this point, the Nnumber of columns within the N number of RS frame includes 187 bytes, asshown in FIG. 7( c).

In this case, a (Nc,Kc)-RS encoding process is performed on each column,so as to generate Nc−Kc(=P) number of parity bytes. Then, the newlygenerated P number of parity bytes is added after the very last byte ofthe corresponding column, thereby creating a column of (187+P) bytes.Herein, as shown in FIG. 7( c), Kc is equal to 187 (i.e., Kc=187), andNc is equal to 187+P (i.e., Nc=187+P). For example, when P is equal to48, (235,187)-RS encoding process is performed so as to create a columnof 235 bytes. When such RS encoding process is performed on all N numberof columns, as shown in FIG. 7( c), a RS frame having the size ofN(row)*(187+P)(column) bytes may be created, as shown in FIG. 7( d). Inorder to simplify the description of the present invention, the RS framehaving the RS parity inserted therein will be referred to as s second RSframe. More specifically, the second RS frame having the structure of(187+P) rows configured of N bytes may be configured.

As shown in FIG. 7( c) or FIG. 7( d), each row of the RS frame isconfigured of N bytes. However, depending upon channel conditionsbetween the transmitting system and the receiving system, error may beincluded in the RS frame. When errors occur as described above, CRC data(or CRC code or CRC checksum) may be used on each row unit in order toverify whether error exists in each row unit. The RS frame encoder 302may perform CRC encoding on the mobile service data being RS encoded soas to create (or generate) the CRC data. The CRC data being generated byCRC encoding may be used to indicate whether the mobile service datahave been damaged while being transmitted through the channel.

The present invention may also use different error detection encodingmethods other than the CRC encoding method. Alternatively, the presentinvention may use the error correction encoding method to enhance theoverall error correction ability of the receiving system. FIG. 7( e)illustrates an example of using a 2-byte (i.e., 16-bit) CRC checksum asthe CRC data. Herein, a 2-byte CRC checksum is generated for N number ofbytes of each row, thereby adding the 2-byte CRC checksum at the end ofthe N number of bytes. Thus, each row is expanded to (N+2) number ofbytes. Equation 1 below corresponds to an exemplary equation forgenerating a 2-byte CRC checksum for each row being configured of Nnumber of bytes.

g(x)=x ¹⁶ +x ¹² +x ⁵+1  Equation 1

The process of adding a 2-byte checksum in each row is only exemplary.Therefore, the present invention is not limited only to the exampleproposed in the description set forth herein. In order to simplify theunderstanding of the present invention, the RS frame having the RSparity and CRC checksum added therein will hereinafter be referred to asa third RS frame. More specifically, the third RS frame corresponds to(187+P) number of rows each configured of (N+2) number of bytes. Asdescribed above, when the process of RS encoding and CRC encoding arecompleted, the (N*187)-byte RS frame is expanded to a (N+2)*(187+P)-byteRS frame.

Based upon an error correction scenario of a RS frame expanded asdescribed above, the data bytes within the RS frame are transmittedthrough a channel in a row direction. At this point, when a large numberof errors occur during a limited period of transmission time, errorsalso occur in a row direction within the RS frame being processed with adecoding process in the receiving system. However, in the perspective ofRS encoding performed in a column direction, the errors are shown asbeing scattered. Therefore, error correction may be performed moreeffectively. At this point, a method of increasing the number of paritydata bytes (P) may be used in order to perform a more intense errorcorrection process. However, using this method may lead to a decrease intransmission efficiency. Therefore, a mutually advantageous method isrequired. Furthermore, when performing the decoding process, an erasuredecoding process may be used to enhance the error correctionperformance.

Additionally, the RS frame encoder 302 according to the presentinvention also performs a row permutation (or interleaving) process insuper frame units in order to further enhance the error correctionperformance when error correction the RS frame. FIG. 8 illustrates anexample of performing a row permutation (or interleaving) process insuper frame units according to the present invention. More specifically,G number of RS frames encoded as shown in FIG. 7 is grouped to form asuper frame, as shown in FIG. 8( a). At this point, since each RS frameis formed of (N+2)*(187+P) number of bytes, one super frame isconfigured to have the size of (N+2)*(187+P)*G bytes.

When a row permutation process permuting each row of the super frameconfigured as described above is performed based upon a pre-determinedpermutation rule, the positions of the rows prior to and after beingpermuted (or interleaved) within the super frame may be altered. Morespecifically, the i^(th) row of the super frame prior to theinterleaving process, as shown in FIG. 8( b), is positioned in thej^(th) row of the same super frame after the row permutation process.The above-described relation between i and j can be easily understoodwith reference to a permutation rule as shown in Equation 2 below.

j=G(i mod(187+P))+┌i/(187+P)┘

i=(187+P)(j mod G)+└j/G┘

where 0≦i, j≦(187+P)G−1; or

where 0≦i, j<(187+P)G  Equation 2

Herein, each row of the super frame is configured of (N+2) number ofdata bytes even after being row-permuted in super frame units.

When all row permutation processes in super frame units are completed,the super frame is once again divided into G number of row-permuted RSframes, as shown in FIG. 8( d), and then provided to the block processor303. Herein, the number of RS parity bytes and the number of columnsshould be equally provided in each of the RS frames, which configure asuper frame. As described in the error correction scenario of a RSframe, in case of the super frame, a section having a large number oferror occurring therein is so long that, even when one RS frame that isto be decoded includes an excessive number of errors (i.e., to an extentthat the errors cannot be corrected), such errors are scatteredthroughout the entire super frame. Therefore, in comparison with asingle RS frame, the decoding performance of the super frame is moreenhanced. When dividing a data group into regions A, B, C, and D, thedata that are to be allocated to regions A, B, C, and D are grouped toform a single RS frame, and the error correction encoding and errordetection encoding processes are performed on to the created RS frame asdescribed above.

FIG. 9A and FIG. 9B illustrate an example of creating an RS frame bygrouping data that are to be allocated to region A/B and creatinganother RS frame by grouping data that are to be allocated to regionC/D, thereby performing error correction encoding and error detectionencoding. More specifically, FIG. 9A illustrates an example of groupingdata that are to be allocated to region A/B so as to create a RS framehaving the size of N1(rows)*187(columns), then performing RS encoding oneach column of the above-described RS frame so as to add P1 number ofparity data bytes in each column, and, then, performing CRC encoding oneach row so as to add a 2-byte CRC checksum in each row. FIG. 9Billustrates an example of grouping data that are to be allocated toregion C/D so as to create a RS frame having the size ofN2(rows)*187(columns), then performing RS encoding on each column of theabove-described RS frame so as to add P2 number of parity data bytes ineach column, and, then, performing CRC encoding on each row so as to adda 2-byte CRC checksum in each row.

At this point, the RS frame encoder 302 may know the RS frameinformation, RS code information, CRC encoding information, data groupinformation, region information within the data group, and so on byreferring to a pre-determined transmission parameter and/or atransmission parameter provided by the service multiplexer 100. Thetransmission parameter is not only referred to for performing theprocesses of creating an RS frame, error correction encoding, and errordetection encoding, but also transmitted to then receiving system inorder to allow the receiving system to perform a normal decodingprocess. Table 1 below shows an example of the RS frame information,i.e., the RS frame mode.

TABLE 1 RS frame mode (2 bits) Description 00 A single RS frame for allregions Primary RS frame only 01 Two separate RS frames. Primary RSframe for region A and B Secondary RS frame for region C and D 10Reserved 11 Reserved

Table 1 illustrates an example of allocating 2 bits in order to indicatethe RS frame mode. For example, when the RS frame mode value is equal to‘00’, this indicates that the mobile service data that are to beallocated to all regions of the corresponding data group is formed as aprimary RS frame. Also, when the RS frame mode value is equal to ‘01’,this indicates that 2 separate RS frames, i.e., a primary RS frame forregion A/B and a secondary RS frame for region C/D, are created. Table 2below shows an example of the RS encoding information, i.e., the RS codemode.

TABLE 2 RS code mode (2 bits) Description 00 (211, 187) RS code, P* = 2401 (223, 187) RS code, P = 36 10 (235, 187) RS code, P = 48 11 Reserved

Table 2 illustrates an example of allocating 2 bits in order to indicatethe RS code mode. For example, when the RS code mode value is equal to‘01’, this indicates that the (223,187)-RS encoding is performed on thecorresponding RS frame, thereby adding 36 bytes of parity data to eachcolumn. The RS code mode indicates the number of parity bytes of therespective RS frame. For example, when the RS frame mode indicates asingle RS frame, only the RS encoding information corresponding to thesingle RS frame is required to be indicated. However, when the RS framemode indicates a plurality of separate RS frames, RS encodinginformation corresponding to each primary and secondary RS frames isindicated. More specifically, it is preferable that the RS code mode isindependently applied to the primary RS frame and the secondary RSframe.

The mobile service data processed with encoding in RS frame units androw permutation (or interleaving) in super frame units by the RS frameencoder 302 are outputted to the block processor 303. The blockprocessor 303 then encodes the inputted mobile service data at a codingrate of MR/NR (wherein, MR is smaller than NR (i.e., MR<NR)) and thenoutputted to the group formatter 304. More specifically, the blockprocessor 303 divides the mobile service data being inputted in byteunits into bit units. Then, the MR number of bits is encoded to NRnumber of bits. Thereafter, the encoded bits are converted back to byteunits and then outputted. For example, if 1 bit of the input data iscoded to 2 bits and outputted, then MR is equal to 1 and NR is equal to2 (i.e., MR=1 and NR=2). Alternatively, if 1 bit of the input data iscoded to 4 bits and outputted, then MR is equal to 1 and NR is equal to4 (i.e., MR=1 and NR=4). Hereinafter, the former coding rate will bereferred to as a coding rate of ½ (½-rate coding), and the latter codingrate will be referred to as a coding rate of ¼ (¼-rate coding), forsimplicity.

Herein, when using the ¼ coding rate, the coding efficiency is greaterthan when using the ½ coding rate, and may, therefore, provide greaterand enhanced error correction ability. For such reason, when it isassumed that the data encoded at a ¼ coding rate in the group formatter304, which is located near the end portion of the system, are allocatedto a region in which the receiving performance may be deteriorated, andthat the data encoded at a ½ coding rate are allocated to a regionhaving excellent receiving performance, the difference in performancemay be reduced.

Meanwhile, the group formatter inserts mobile service data that areoutputted from the block processor 303 in corresponding regions within adata group, which is configured in accordance with a pre-defined rule.Also, with respect to the data deinterleaving process, each place holderor known data (or known data place holders) are also inserted incorresponding regions within the data group. At this point, the datagroup may be divided into at least one hierarchical region. Herein, thetype of mobile service data being inserted in each region may varydepending upon the characteristics of each hierarchical region.Furthermore, each region may, for example, be divided based upon thereceiving performance within the data group.

In an example given in the present invention, a data group is dividedinto regions A, B, C, and D in a data configuration prior to datadeinterleaving. At this point, the group formatter 304 allocates themobile service data, which are inputted after being RS encoded and blockencoded, to each of the corresponding regions by referring to thetransmission parameter. FIG. 10A illustrates an alignment of data afterbeing data interleaved and identified, and FIG. 10B illustrates analignment of data before being data interleaved and identified. Morespecifically, a data structure identical to that shown in FIG. 10A istransmitted to a receiving system. In other words, one transport packetis interleaved by the data interleaver so as to be scattered to aplurality of data segments, thereby being transmitted to the receivingsystem. FIG. 10A illustrates an example of one data group beingscattered to 170 data segments. At this point, since one 207-byte packethas the same amount of data as one data segment, the packet that is notyet processed with data interleaving may be used as the data segment.

Also, the data group configured to have the same structure as the datastructure shown in FIG. 10A is inputted to the data deinterleaver 305.FIG. 10A shows an example of dividing a data group prior to beingdata-interleaved into 10 MPH blocks (i.e., MPH block 1 (B1) to MPH block10 (B10)). In this example, each MPH block has the length of 16segments. Referring to FIG. 10A, only the RS parity data are allocatedto portions of the first 5 segments of the MPH block 1 (B1) and the last5 segments of the MPH block 10 (B10). The RS parity data are excluded inregions A to D of the data group. When it is assumed that one data groupis divided into regions A, B, C, and D, each MPH block may be includedin any one of region A to region D depending upon the characteristic ofeach MPH block within the data group.

Herein, the data group is divided into a plurality of regions to be usedfor different purposes. More specifically, a region of the main servicedata having no interference or a very low interference level may beconsidered to have a more resistant (or stronger) receiving performanceas compared to regions having higher interference levels. Additionally,when using a system inserting and transmitting known data in the datagroup, and when consecutively long known data are to be periodicallyinserted in the mobile service data, the known data having apredetermined length may be periodically inserted in the region havingno interference from the main service data (i.e., a region wherein themain service data are not mixed). However, due to interference from themain service data, it is difficult to periodically insert known data andalso to insert consecutively long known data to a region havinginterference from the main service data.

Referring to FIG. 10A, MPH block 4 (B4) to MPH block 7 (B7) correspondto regions without interference of the main service data. MPH block 4(B4) to MPH block 7 (B7) within the data group shown in FIG. 10Acorrespond to a region where no interference from the main service dataoccurs. In this example, a long known data sequence is inserted at boththe beginning and end of each MPH block. In the description of thepresent invention, the region including MPH block 4 (B4) to MPH block 7(B7) will be referred to as “region A”. As described above, when thedata group includes region A having a long known data sequence insertedat both the beginning and end of each MPH block, the receiving system iscapable of performing equalization by using the channel information thatcan be obtained from the known data. Therefore, the strongest equalizingperformance may be yielded (or obtained) from one of region A to regionD.

In the example of the data group shown in FIG. 10A, MPH block 3 (B3) andMPH block 8 (B8) correspond to a region having little interference fromthe main service data. Herein, a long known data sequence is inserted inonly one side of each MPH block B3 and B8. More specifically, due to theinterference from the main service data, a long known data sequence isinserted at the end of MPH block 3 (B3), and another long known datasequence is inserted at the beginning of MPH block 8 (B8). In thepresent invention, the region including MPH block 3 (B3) and MPH block 8(B8) will be referred to as “region B”. As described above, when thedata group includes region B having a long known data sequence insertedat only one side (beginning or end) of each MPH block, the receivingsystem is capable of performing equalization by using the channelinformation that can be obtained from the known data. Therefore, astronger equalizing performance as compared to region C/D may be yielded(or obtained).

Referring to FIG. 10A, MPH block 2 (B2) and MPH block 9 (B9) correspondto a region having more interference from the main service data ascompared to region B. A long known data sequence cannot be inserted inany side of MPH block 2 (B2) and MPH block 9 (B9). Herein, the regionincluding MPH block 2 (B2) and MPH block 9 (B9) will be referred to as“region C”. Finally, in the example shown in FIG. 10A, MPH block 1 (B1)and MPH block 10 (B10) correspond to a region having more interferencefrom the main service data as compared to region C. Similarly, a longknown data sequence cannot be inserted in any side of MPH block 1 (B1)and MPH block 10 (B10). Herein, the region including MPH block 1 (B1)and MPH block 10 (B10) will be referred to as “region D”. Since regionC/D is spaced further apart from the known data sequence, when thechannel environment undergoes frequent and abrupt changes, the receivingperformance of region C/D may be deteriorated.

FIG. 10B illustrates a data structure prior to data interleaving. Morespecifically, FIG. 10B illustrates an example of 118 data packets beingallocated to a data group. FIG. 10B shows an example of a data groupconsisting of 118 data packets, wherein, based upon a reference packet(e.g., a 1^(st) packet (or data segment) or 157^(th) packet (or datasegment) after a field synchronization signal), when allocating datapackets to a VSB frame, 37 packets are included before the referencepacket and 81 packets (including the reference packet) are includedafterwards. The size of the data groups, number of hierarchical regionswithin the data group, the size of each region, the number of MPH blocksincluded in each region, the size of each MPH block, and so on describedabove are merely exemplary. Therefore, the present invention will not belimited to the examples described above.

When it is assumed that the data group is divided into a plurality ofhierarchical regions, as described above, the block processor 303 mayencode the mobile service data, which are to be inserted to each regionbased upon the characteristic of each hierarchical region, at differentcoding rates. For example, the block processor 303 may encode the mobileservice data, which are to be inserted in region A/B, at a coding rateof ½. Then, the group formatter 304 may insert the ½-rate encoded mobileservice data to region A/B. Also, the block processor 303 may encode themobile service data, which are to be inserted in region C/D, at a codingrate of ¼ having higher error correction ability than the ½-coding rate.Thereafter, the group formatter 304 may insert the ½-rate encoded mobileservice data to region C/D. In another example, the block processor 303may encode the mobile service data, which are to be inserted in regionC/D, at a coding rate having higher error correction ability than the¼-coding rate. Then, the group formatter 304 may either insert theencoded mobile service data to region C/D, as described above, or leavethe data in a reserved region for future usage.

According to another embodiment of the present invention, the blockprocessor 303 may perform a MR/NR-rate encoding process in SCCC blockunits. Herein, the SCCC block includes at least one MPH block. At thispoint, when MR/NR-rate encoding is performed in a MPH block unit, theMPH block and the SCCC block become identical to one another. Forexample, the MPH block 1 (B1) may be encoded at the coding rate of ½,the MPH block 2 (B2) may be encoded at the coding rate of ¼, and the MPHblock 3 (B3) may be encoded at the coding rate of ½. The coding ratesare applied respectively to the remaining MPH blocks.

Alternatively, a plurality of MPH blocks within regions A, B, C, and Dmay be grouped into one SCCC block, thereby being encoded at a codingrate of MR/NR in SCCC block units. Accordingly, the receivingperformance of region C/D may be enhanced. For example, MPH block 1 (B1)to MPH block 5 (B5) may be grouped into one SCCC block and then encodedat a coding rate of ½. Thereafter, the group formatter 304 may insertthe ½-rate encoded mobile service data to part of the above-describedregion A to region D. Furthermore, MPH block 6 (B6) to MPH block 10(B10) may be grouped into one SCCC block and then encoded at a codingrate of ¼. Thereafter, the group formatter 304 may insert the ¼-rateencoded mobile service data to another part of the above-describedregion A to region D.

In this case, one data group may consist of two SCCC blocks. Accordingto another embodiment of the present invention, one SCCC block may beformed by grouping two MPH blocks. For example, MPH block 1 (B1) and MPHblock 6 (B6) may be grouped into one SCCC block. Similarly, MPH block 2(B2) and MPH block 7 (B7) may be grouped into another SCCC block. Also,MPH block 3 (B3) and MPH block 8 (B8) may be grouped into another SCCCblock. And, MPH block 4 (B4) and MPH block 9 (B9) may be grouped intoanother SCCC block. Furthermore, MPH block 5 (B5) and MPH block 10 (B10)may be grouped into another SCCC block. In the above-described example,the data group may consist of 10 MPH blocks and 5 MPH blocks.Accordingly, in a data (or signal) receiving environment undergoingfrequent and severe channel changes, the receiving performance ofregions C and D, which is relatively more deteriorated than thereceiving performance of region A, may be reinforced. Furthermore, sincethe number of mobile service data symbols increases more and more fromregion A to region D, the error correction encoding performance becomesmore and more deteriorated. Therefore, when grouping a plurality of MPHblock to form one SCCC block, such deterioration in the error correctionencoding performance may be reduced.

As described-above, when the block processor 303 performs encoding at aMR/NR-coding rate, information associated with SCCC should betransmitted to the receiving system in order to accurately recover themobile service data. An example of SCCC block information, i.e., SCCCblock mode, is shown in Table 3 below.

TABLE 3 SCCC block mode (2 bits) Description 00 SCCC block is identicalwith MPH block 01 Reserved 10 Reserved 11 Reserved

More specifically, Table 3 shows an example of 2 bits being allocated inorder to indicate the SCCC block mode. For example, when the SCCC blockmode value is equal to ‘00’, this indicates that the SCCC block and theMPH block are identical to one another.

Although it is not indicated in Table 3, if one data block consists oftwo SCCC blocks, as described above, the corresponding information mayalso be indicated as the SCCC block mode. For example, when the SCCCblock mode value is equal to ‘01’, this may indicate that one data groupis configured of two SCCC block. Also, when the SCCC block mode value isequal to ‘10’, this may indicate that 2 MPH block s form one SCCC blockand that, accordingly, one data group is configured of 5 SCCC blocks.Herein, the number of MPH block included in the SCCC block and theposition of each MPH block may vary depending upon the design of thesystem designer. Therefore, the present invention will not be limitedonly to the example presented in the description of the presentinvention. Furthermore, expansion in the SCCC mode information may alsobe made.

An example of a coding rate information of the SCCC block, i.e., SCCCouter code mode mode, is shown in Table 4 below.

TABLE 4 SCCC outer code mode (2 bits) Description 00 Outer code rate ofSCCC block is ½ rate 01 Outer code rate of SCCC block is ¼ rate 10Reserved 11 Reserved

More specifically, Table 4 shows an example of 2 bits being allocated inorder to indicate the coding rate information of the SCCC block. Forexample, when the SCCC outer code mode value is equal to ‘00’, thisindicates that the coding rate of the corresponding SCCC block is ½.And, when the SCCC outer code mode value is equal to ‘01’, thisindicates that the coding rate of the corresponding SCCC block is ¼.

If the SCCC block mode value of Table 3 indicates ‘00’, the SCCC outercode mode may indicate the coding rate of each MPH block with respect toeach MPH block. In this case, since it is assumed that one data groupincludes 10 MPH blocks and that 2 bits are allocated for each SCCC blockmode, a total of 20 bits are required for indicating the SCCC blockmodes of the 10 MPH modes. In another example, when the SCCC block modevalue of Table 3 indicates ‘00’, the SCCC outer code mode may indicatethe coding rate of each region with respect to each region within thedata group. In this case, since it is assumed that one data groupincludes 4 regions (i.e., regions A, B, C, and D) and that 2 bits areallocated for each SCCC block mode, a total of 8 bits are required forindicating the SCCC block modes of the 4 regions.

Also, apart from the encoded mobile service data outputted from theblock processor 303, the group formatter 304 also inserts MPEG headerplace holders, non-systematic RS parity place holders, main service dataplace holders, which are associated with the data deinterleaving in alater process, as shown in FIG. 10A. Herein, the main service data placeholders are inserted because the mobile service data bytes and the mainservice data bytes are alternately mixed with one another in regions Bto D based upon the input of the data deinterleaver, as shown in FIG.10A. For example, based upon the data outputted after datadeinterleaving, the place holder for the MPEG header may be allocated atthe very beginning of each packet. Furthermore, the group formatter 304either inserts known data generated in accordance with a pre-determinedmethod or inserts known data place holders for inserting the known datain a later process. Additionally, place holders for initializing thetrellis encoding module 256 are also inserted in the correspondingregions. For example, the initialization data place holders may beinserted in the beginning of the known data sequence.

Meanwhile, since the size of an RS frame encoded by the block processor303 at the coding rate MR/NR is larger than the size of a data group,the mobile service data within an RS frame are divided and inserted intoa plurality of data groups. In the example of the present invention, themobile service data within an RS frame are allocated to thecorresponding region of a plurality of data groups, each having the samesize and corresponding to the RS frame. Herein, the number of datagroups having the same size and corresponding to the RS frame may differdepending upon the size of the RS frame that is being encoded at acoding rate of MR/NR.

However, since the data within an RS frame are inserted in thecorresponding regions of a plurality of data groups, each having thesame size, remaining data bytes may occur in particular regions ofparticular data groups. More specifically, remaining data bytes mayoccur when the size of an RS frame encoded at a coding rate of MR/NR islarger than the size of a corresponding region of the plurality of datagroups, each having the same size. In other words, remaining data bytesmay occur in particular regions within the plurality of data groupscorresponding to the RS frame depending upon the size of the RS frames,the size and number of divided data groups, the number of mobile servicedata bytes that may be inserted into each data group, the coding rate ofthe corresponding region, the number of RS parity bytes, whether or nota CRC checksum has been allocated, and, if any, the number of CRCchecksums allocated.

When dividing the RS frame into a plurality of data groups having thesame size, and when remaining data bytes occur in the corresponding RSframe, K number of dummy bytes are added to the corresponding RS frame,wherein K is equal to the number of remaining data bytes within the RSframe. Then, the dummy byte-added RS frame is divided into a pluralityof data groups. This process is illustrated in FIG. 11. Morespecifically, FIG. 11 illustrates an example of processing K number ofremaining data bytes, which are produced by dividing the RS frame havingthe size of (N+2)*(187+P) bytes into M number of data groups havingequal sizes. In this case, as shown in FIG. 11( a), K number of dummybytes are added to the RS frame having the size of (N+2)*(187+P) bytes.Subsequently, the RS frame is read in row units, thereby being dividedinto M number of data groups, as shown in FIG. 11( b). At this point,each data group has the size of NoBytesPerGrp bytes. This may bedescribed by Equation 3 shown below.

M×NoBytesPerGrp=(N+2)×(187+P)×K  Equation 3

Herein, NoBytesPerGrp indicates the number of bytes allocated for eachgroup (i.e., the Number of Bytes Per Group). More specifically, the sizecorresponding to the number of byte in one RS frame+K bytes is equal tothe size of the M number of data groups.

The output of the group formatter 304 is inputted to the datadeinterleaver 305. And, the data deinterleaver 305 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 306. More specifically, when the data and place holderswithin the data group configured, as shown in FIG. 10A, aredeinterleaved by the data deinterleaver 305, the data group beingoutputted to the packet formatter 306 is configured to have thestructure shown in FIG. 10B.

The packet formatter 306 removes the main service data place holders andthe RS parity place holders that were allocated for the deinterleavingprocess from the deinterleaved data being inputted. Then, the packetformatter 306 groups the remaining portion and replaces the 4-byte MPEGheader place holder with an MPEG header having a null packet PID (or anunused PID from the main service data packet). Also, when the groupformatter 304 inserts known data place holders, the packet formatter 306may insert actual known data in the known data place holders, or maydirectly output the known data place holders without any modification inorder to make replacement insertion in a later process. Thereafter, thepacket formatter 306 identifies the data within the packet-formatteddata group, as described above, as a 188-byte unit mobile service datapacket (i.e., MPEG TS packet), which is then provided to the packetmultiplexer 240.

The packet multiplexer 240 multiplexes the data group packet-formattedand outputted from the packet formatter 306 and the main service datapacket outputted from the packet jitter mitigator 220 in accordance witha pre-defined multiplexing method. Then, the packet multiplexer 240outputs the multiplexed data packets to the data randomizer 251 of thepost-processor 250. The multiplexing method and multiplexing rules ofthe packet multiplexer 240 will be described in more detail in a laterprocess.

Also, since a data group including mobile service data in-between thedata bytes of the main service data is multiplexed (or allocated) duringthe packet multiplexing process, the shifting of the chronologicalposition (or place) of the main service data packet becomes relative.Also, a system object decoder (i.e., MPEG decoder) for processing themain service data of the receiving system, receives and decodes only themain service data and recognizes the mobile service data packet as anull data packet. Therefore, when the system object decoder of thereceiving system receives a main service data packet that is multiplexedwith the data group, a packet jitter occurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 240 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data in the object decoder isrelatively small, the packet jitter may cause considerable problem. Morespecifically, due to the packet jitter, an overflow or underflow mayoccur in the buffer for the main service data of the receiving system(e.g., the buffer for the audio data) Therefore, the packet jittermitigator 220 re-adjusts the relative position of the main service datapacket so that the overflow or underflow does not occur in the systemobject decoder.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The packet jitter mitigator 220 repositions the audio datapackets in the main service data section so that the audio data packetsof the main service data can be as equally and uniformly aligned andpositioned as possible. Additionally, when the positions of the mainservice data packets are relatively re-adjusted, associated programclock reference (PCR) values may also be modified accordingly. The PCRvalue corresponds to a time reference value for synchronizing the timeof the MPEG decoder. Herein, the PCR value is inserted in a specificregion of a TS packet and then transmitted.

In the example of the present invention, the packet jitter mitigator 220also performs the operation of modifying the PCR value. The output ofthe packet jitter mitigator 220 is inputted to the packet multiplexer240. As described above, the packet multiplexer 240 multiplexes the mainservice data packet outputted from the packet jitter mitigator 220 withthe mobile service data packet outputted from the pre-processor 230 intoa burst structure in accordance with a pre-determined multiplexing rule.Then, the packet multiplexer 240 outputs the multiplexed data packets tothe data randomizer 251 of the post-processor 250.

If the inputted data correspond to the main service data packet, thedata randomizer 251 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 251. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 252.

On the other hand, if the inputted data correspond to the mobile servicedata packet, the data randomizer 251 may randomize only a portion of thedata packet. For example, if it is assumed that a randomizing processhas already been performed in advance on the mobile service data packetby the pre-processor 230, the data randomizer 251 deletes thesynchronization byte from the 4-byte MPEG header included in the mobileservice data packet and, then, performs the randomizing process only onthe remaining 3 data bytes of the MPEG header. Thereafter, therandomized data bytes are outputted to the RS encoder/non-systematic RSencoder 252. More specifically, the randomizing process is not performedon the remaining portion of the mobile service data excluding the MPEGheader. In other words, the remaining portion of the mobile service datapacket is directly outputted to the RS encoder/non-systematic RS encoder252 without being randomized. Also, the data randomizer 251 may or maynot perform a randomizing process on the known data (or known data placeholders) and the initialization data place holders included in themobile service data packet.

The RS encoder/non-systematic RS encoder 252 performs an RS encodingprocess on the data being randomized by the data randomizer 251 or onthe data bypassing the data randomizer 251, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 253. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 252performs the same systematic RS encoding process as that of theconventional broadcasting system, thereby adding the 20-byte RS paritydata at the end of the 187-byte data. Alternatively, if the inputteddata correspond to the mobile service data packet, the RSencoder/non-systematic RS encoder 252 performs a non-systematic RSencoding process. At this point, the 20-byte RS parity data obtainedfrom the non-systematic RS encoding process are inserted in apre-decided parity byte place within the mobile service data packet.

The data interleaver 253 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 253 is inputted to theparity replacer 254 and to the non-systematic RS encoder 255. Meanwhile,a process of initializing a memory within the trellis encoding module256 is primarily required in order to decide the output data of thetrellis encoding module 256, which is located after the parity replacer254, as the known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoding module 256 should first be initializedbefore the received known data sequence is trellis-encoded. At thispoint, the beginning portion of the known data sequence that is receivedcorresponds to the initialization data place holder and not to theactual known data. Herein, the initialization data place holder has beenincluded in the data by the group formatter within the pre-processor 230in an earlier process. Therefore, the process of generatinginitialization data and replacing the initialization data place holderof the corresponding memory with the generated initialization data arerequired to be performed immediately before the inputted known datasequence is trellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encodingmodule 256. Further, due to the newly replaced initialization data, aprocess of newly calculating the RS parity and replacing the RS parity,which is outputted from the data interleaver 253, with the newlycalculated RS parity is required. Therefore, the non-systematic RSencoder 255 receives the mobile service data packet including theinitialization data place holders, which are to be replaced with theactual initialization data, from the data interleaver 253 and alsoreceives the initialization data from the trellis encoding module 256.

Among the inputted mobile service data packet, the initialization dataplace holders are replaced with the initialization data, and the RSparity data that are added to the mobile service data packet are removedand processed with non-systematic RS encoding. Thereafter, the new RSparity obtained by performing the non-systematic RS encoding process isoutputted to the parity replacer 255. Accordingly, the parity replacer255 selects the output of the data interleaver 253 as the data withinthe mobile service data packet, and the parity replacer 255 selects theoutput of the non-systematic RS encoder 255 as the RS parity. Theselected data are then outputted to the trellis encoding module 256.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization dataplace holders that are to be replaced, is inputted, the parity replacer254 selects the data and RS parity that are outputted from the datainterleaver 253. Then, the parity replacer 254 directly outputs theselected data to the trellis encoding module 256 without anymodification. The trellis encoding module 256 converts the byte-unitdata to symbol units and performs a 12-way interleaving process so as totrellis-encode the received data. Thereafter, the processed data areoutputted to the synchronization multiplexer 260.

The synchronization multiplexer 260 inserts a field synchronizationsignal and a segment synchronization signal to the data outputted fromthe trellis encoding module 256 and, then, outputs the processed data tothe pilot inserter 271 of the transmission unit 270. Herein, the datahaving a pilot inserted therein by the pilot inserter 271 are modulatedby the modulator 272 in accordance with a pre-determined modulatingmethod (e.g., a VSB method). Thereafter, the modulated data aretransmitted to each receiving system though the radio frequency (RF)up-converter 273.

Multiplexing method of Packet Multiplexer 240

Meanwhile, in the packet multiplexer 240, a data group is assigned to aVSB frame based upon a starting point of a slot. Herein, main servicedata are allocated in between data groups so as to perform themultiplexing process. In the example of the present invention, a portionof a data group starting from the N^(th) data packet of thecorresponding data group is assigned to a beginning (or starting point)of a slot (i.e., the first data segment of the current slot) based upona data structure prior to data interleaving. Herein, N is an integer.For example, when N is equal to 1 (i.e., N=1), a portion of a data groupstarting from the 1^(st) data packet of the corresponding data group isassigned to the beginning of the first data segment of the current slot.Also, when N is equal to 38 (i.e., N=38), a portion of a data groupstarting from the 38^(th) data packet of the corresponding data group isassigned to the beginning of the first data segment of the current slot.Furthermore, when N=1, one data group may be assigned to one slot.

FIG. 12 illustrates an example of assigning a 38^(th) data packet of adata group to a starting point of a slot (i.e., the first data segmentof the current slot) based upon a data structure prior to datainterleaving. In this case, a range of data packets starting from the1^(st) packet to the 37^(th) packet of the corresponding data group isassigned to the previous slot. Also, as shown in FIG. 12, when it isassumed that a data group is assigned for each slot within the VSBframe, the field synchronization multiplexer 260 may insert a fieldsynchronization signal after the 37^(th) data packet of the data groupbeing assigned to the 1^(st) slot (Slot 1) of each field. In this case,the receiving system may also use the field synchronization signal forthe channel equalizing process, thereby enhancing the receivingperformance of the corresponding data group.

As described above, the data of a RS frame is divided into a pluralityof data groups and assigned to the corresponding region by the groupformatter 304. Then, the data groups pass through the data deinterleaver305 and the packet formatter 306 and are multiplexed with the mainservice data by the packet multiplexer 240 in accordance with apre-decided multiplexing rule. In the description of the presentinvention, the plurality of data groups having data within an RS frameassigned (or allocated) thereto will be referred to as an “ensemble”.Herein, since a plurality of mobile services may be included in an RSframe, an ensemble may also include a plurality of mobile services. Morespecifically, an ensemble may transmit multiple data streams.

According to an embodiment of the present invention, the data groupsincluded in an ensemble are allocated to be spaced apart from oneanother as possible within the MPH frame. Thus, the system can becapable of responding promptly and effectively to any burst error thatmay occur within an ensemble. Additionally, since the data groups foreach ensemble are allocated based upon the MPH frames, the method forallocating the data groups may vary depending upon the corresponding MPHframe. Furthermore, the data groups are equally (or identically)allocated to each sub-frame within an MPH frame. According to theembodiment of the present invention, in each sub-frame, the data groupsare serially allocated to a group space having 4 slots (i.e., 1 VSBframe) from left to right. Therefore, a number of groups of one ensembleper sub-frame (NOG) may correspond to any one integer from ‘1’ to ‘8’.Herein, since one MPH frame includes 5 sub-frames, the total number ofdata groups within an ensemble that can be allocated to an MPH frame maycorrespond to any one multiple of ‘5’ ranging from ‘5’ to ‘40’.

FIG. 13 illustrates an example of multiple data groups of a singleensemble being allocated (or assigned) to an MPH frame. Morespecifically, FIG. 13 illustrates an example of a plurality of datagroups included in an ensemble having an NOG of ‘3’ being allocated toan MPH frame. Referring to FIG. 13, 3 data groups are sequentiallyassigned to a sub-frame at a cycle period of 4 slots. Accordingly, whenthis process is equally performed in the 5 sub-frames included in thecorresponding MPH frame, 12 data groups are assigned to a single MPHframe. Herein, the 15 data groups correspond to data groups included inan ensemble. Therefore, since one sub-frame is configured of 4 VSBframe, and since the NOG is equal to ‘3’, the data group of thecorresponding ensemble is not assigned to 1 VSB frame within eachsub-frame.

For example, when the RS code mode of a corresponding RS frame is equalto ‘00’ (i.e., when 24 bytes of parity data are added to thecorresponding RS frame by an RS encoding process), the parity dataoccupies approximately 11.37% (=24/(187+24)×100) of the total code wordlength. Meanwhile, when the NOG is equal to ‘3’, and when the datagroups of an ensemble are assigned, as shown in FIG. 13, a total of 15data groups form an RS frame. Accordingly, even when an error occurs inan entire data group due to a burst noise within a channel, thepercentile is merely 6.67% (=1/15×100). Therefore, all errors may becorrected by an erasure RS decoding process. More specifically, when theerasure RS decoding is performed, a number of channel errorscorresponding to the number of RS parity bytes may be corrected. Bydoing so, the receiving system may correct the error of at least onedata group within one ensemble. Thus, the minimum burst noise lengthcorrectable by a RS frame is over 1 VSB frame. Meanwhile, when datagroups of an ensemble are assigned as described above, either mainservice data may be assigned between each data group, or data groupscorresponding to different ensembles may be assigned between each datagroup. More specifically, data groups corresponding to multipleensembles may be assigned to one MPH frame.

Basically, the method of assigning data groups corresponding to multipleensembles is very similar to the method of assigning data groupscorresponding to a single ensemble. In other words, data groups includedin other ensembles that are to be assigned to an MPH frame are alsorespectively assigned according to a cycle period of 4 slots. At thispoint, a data group of a different ensemble may be sequentially assignedto a sub-frame starting from the 1^(st) VSB frame (i.e., VSB frame 1).Alternatively, a data group of a previous ensemble may be assigned in acircular method starting from a VSB frame to which a data group has notyet been assigned. For example, when it is assumed that data groupscorresponding to an ensemble are assigned as shown in FIG. 13, datagroups corresponding to the next ensemble may be assigned to a sub-framestarting either from the 1^(st) VSB frame (VSB frame 1) or the 4^(th)VSB frame (VSB frame 4).

FIG. 14 illustrates an example of assigning data groups corresponding tomultiple ensembles within an MPH frame. More specifically, FIG. 14illustrates an example of assigning data groups of a 1^(st) ensemblehaving an NOG equal to ‘3’ (i.e., ensemble 1 with NOG=3) and data groupsof a 2^(nd) ensemble having an NOG equal to ‘4’ (i.e., ensemble 2 withNOG=4) to an MPH frame. Referring to FIG. 14, when the process ofassigning data groups corresponding to ensemble 1 is completed, datagroups corresponding to ensemble 2 are assigned starting from the 4^(th)VSB frame of the 1^(st) sub-frame (i.e., sub-frame 1) within thecorresponding MPH frame. More specifically, the 1^(st) data group of the2^(nd) ensemble (ensemble 2) may be assigned to the 4^(th) VSB frame ofsub-frame 1, the 2^(nd) data group may be assigned to the 1^(st) VSBframe of sub-frame 1, the 3^(rd) data group may be assigned to the2^(nd) VSB frame of sub-frame 1, and the 4^(th) data group may beassigned to the 3^(rd) VSB frame of sub-frame 1. Similarly, the datagroups of ensemble 2 are respectively assigned to the 2^(nd) sub-frame(i.e., sub-frame 2) and onwards by the same order. Referring to FIG. 14,the group number corresponds to the order by which the data groups areassigned to each sub-frame.

At this point, the data groups are assigned to each VSB frame by theorder of the 1^(st) slot (slot 1), the 2^(nd) slot (slot 2), the 3^(rd)slot (slot 3), and the 4^(th) slot (slot 4). For example, when four datagroups are sequentially assigned to slot 1 of four VSB frame within asub-frame, the four subsequent data groups are sequentially assigned toslot 3 of each VSB frame of the corresponding sub-frame. Then, the nextfour data groups are sequentially assigned to slot 2 of each VSB frameof the corresponding sub-frame, and the four subsequent data groups aresequentially assigned to slot 4 of each VSB frame of the correspondingsub-frame. Therefore, when it is assumed that 16 data groups areassigned to 4 VSB frames within a sub-frame by performing theabove-described process, in the 1^(st) VSB frame (VSB frame 1), the1^(st) data group is assigned to slot 1, the 5^(th) data group isassigned to slot 3, the 9^(th) data group is assigned to slot 2, and the13^(th) data group is assigned to slot 4.

Meanwhile, when it is assumed that the minimum number of data groups ofan ensemble that can be assigned to a sub-frame is equal to ‘1’, one MPHframe may transmit up to a maximum number of 16 different ensembles.This is because a maximum total of 16 data groups may be transmitted toone sub-frame. The above-described rule for multiplexing (or assigning)data groups can be expressed by the following Equation 4:

SLOT_(i)=((4(i−1)+0_(i)) mod 16)+1  Equation 4

Herein,

-   -   0_(i)=0 if 1≦i≦4,    -   0_(i)=2 else if i≦8,    -   0_(i)=1 else if i≦˜12,    -   0_(i)=3 else.

Also, 1≦SLOT_(i)≦16, and 1≦i≦TNOG

More specifically, SLOT_(i) indicates a slot being assigned with ani^(th) data group within a sub-frame, and i represents the slot numberwithin a sub-frame. Herein, i correspond to any one number within therange of 1 to 16. Also, TNOG represents a total number of data groupsassigned to all ensembles for one sub-frame.

For example, it is assumed that 2 ensembles are assigned to one MPHframe, and that NOG2 of ensemble 2 is equal to ‘4’ (i.e., NOG2=4).Herein, NOGj represents the number of data groups included in a j^(th)ensemble (ensemble j) of a sub-frame. In this case, within onesub-frame, the data groups of ensemble 1 are assigned to slot 1, slot 5,and slot 9 (wherein, i=1, 2, 3), and the data groups of ensemble 2 areassigned to slot 13, slot 3, slot 7, and slot 11 (wherein, j=4, 5, 6,7). Herein, a portion of the RS frame corresponding to ensemble 2 may bemapped in a time order to the 3^(rd) data group, the 7^(th) data group,the 1^(th) data group, and the 13^(th) data group. More specifically,when an RS frame is divided and mapped into a plurality of data groups,instead of mapping the RS frame in a slot order, which is decided bysubstituting an integer for the group number (i) in Equation 4, the RSframe is mapped in a time order starting from the closest slot. In otherwords, when the NOG of an ensemble is decided, the position of each slotto which the data groups of a corresponding ensemble are transmittedwithin a sub-frame is also decided. Accordingly, when the RS frame ofthe corresponding ensemble is divided and transmitted to a plurality ofdata groups, the RS frame is mapped and transmitted in a time order ofthe corresponding slots.

Additionally, each sub-frames within the above-described MPH frame, eachVSB frame within each sub-frame, and the rule for multiplexing the datagroups in each slot within each VSB frame may be pre-decided and sharedby the transmitting system and the receiving system. When thetransmitting system transmits to the receiving system NOG information ofall ensembles that are sent to the corresponding MPH frame, thereceiving system can know to which slot the data group of each slot ismapped by using Equation 4. In this case, the group mapping of allensembles can be known. Hereinafter, the information on which slot thedata groups configuring one ensemble are mapped within a sub-frame willbe referred to as an ensemble MAP. However, when the NOG information ofall ensembles are transmitted as signaling information to all datagroups of all ensembles as described above, by receiving the data groupsof an ensemble, thereby receiving the signaling information, it isadvantageous in that the ensemble MAP for all ensembles existing withinthe corresponding MPH frame can be known. However, the disadvantage isthat the signaling information may be transmitted excessively.

One of the methods for minimizing the amount of signaling information isto transmit only the NOG of the corresponding ensemble. However, whentransmitting only the NOG, the ensemble MAP of the correspondingensemble cannot be obtained by using Equation 4. In order to accuratelyobtain the ensemble MAP using Equation 4, not only the NOG but also astarting group number (SGN) of the ensemble should be given.

In other words, when given the NOG and SGN of the correspondingensemble, the ensemble MAP of the corresponding ensemble can beobtained. Herein, the SGN indicates the number of the data group, whichmay be substituted by i in Equation 4. More specifically, referring toFIG. 14, the starting group number (SGN) of ensemble 2 is equal to ‘4’.This is because the NOG of ensemble 3 is equal to ‘3’. Meanwhile, inorder to enable the receiving system to receive only the data of thedesired (or requested) ensemble, the transmitting system is required totransmit an identifier for each ensemble (i.e., an ensemble identifier,hereinafter referred to as “ensemble_id”) to the receiving system. Sincethe maximum number of ensembles that can be transmitted (i.e., themaximum number of transmittable ensembles) within an MPH frame is equalto ‘16’, the ensemble_id may be indicated as 4 bits.

Unlike in real-time data broadcasting, such as audio and video data,channel change time is not as significant (or important) as in non-realtime data broadcasting. Therefore, the data of a particular ensemble isnot required to be transmitted for each MPH frame. Instead, the data maybe transmitted once for each set of multiple MPH frames. For example,data may be transmitted once for each 2 MPH frames. In this case, thedata rate of the corresponding ensemble may be reduced by ½ as comparedto when transmitting data for each MPH frame. Accordingly, when abroadcast station assigns the data rate of an MPH broadcast program, thedata may be provided with smaller resolution, thereby increasing theefficiency in applying broadcast programs. In order to do so, anensemble transmission period (hereinafter referred to as “ETP”) is addedto the signaling information, thereby indicating that the correspondingensemble is transmitted once for k number of MPH frames. As describedabove, in order to enable the receiving system to know the ensemble MAPof the corresponding ensemble, the transmitting system transmitssignaling information, such as ensemble_id, SGN, NOG, ETP, and so on, ofthe corresponding ensemble.

FIG. 16A describes the SGN, wherein SGN is configured of 4 bits. In thiscase, the value of SGN may be equal to any one value ranging from ‘1’ to‘16’. FIG. 16B describes the NOG, wherein NOG is configured of 3 bits.Herein, the value of NOG may be equal to any one value ranging from ‘1’to ‘8’. Furthermore, FIG. 16C describes the ETP, wherein ETP isconfigured of 2 bits. The ETP indicates the MPH frame cycle periodaccording to which the corresponding ensemble is being transmitted.

FIG. 15 illustrates an example of 3 ensembles existing in one MPH frame.Referring to FIG. 15, 3 data groups of the 1^(st) ensemble (E1), 2 datagroups of the 2^(nd) ensemble (E2), and 2 data groups of the 3^(rd)ensemble (E3) exist in one sub-frame. Therefore, in the 1^(st) ensemble,the SGN is equal to ‘1’ (i.e., SGN=1) and the NOG is equal to ‘3’ (i.e.,NOG=3). Also, in the 2^(nd) ensemble, the SGN is equal to ‘4’ (i.e.,SGN=4) and the NOG is equal to ‘2’ (i.e., NOG=2). Similarly, in the3^(rd) ensemble, the SGN is equal to ‘6’ (i.e., SGN=6) and the NOG isequal to ‘2’ (i.e., NOG=2). In FIG. 15, different values may be givenfor the ensemble_id of each ensemble. Also, different values may begiven for the ETP.

Meanwhile, in the receiving system, by turning the power on during asection, wherein the data groups of a requested ensemble are assigned,so as to receive data, and by turning the power off during the remainingsections, excessive power consumption of the receiving system may bereduced. Such characteristic is particularly advantageous in portableand mobile receivers that require low power consumption. For example, itis assumed that data groups of the 1^(st) ensemble with NOG=3 and datagroups of the 2^(nd) ensemble with NOG=2 are assigned to an MPH frame,as shown in FIG. 17( a). It is also assumed that the user uses a keypadprovided on a remote controller or terminal to select a mobile serviceincluded in the 1^(st) ensemble. In this case, the receiving systemturns the power on only during a section having the data groups of the1^(st) ensemble assigned thereto, and turns the power off during theremaining sections, as shown in FIG. 17( b), thereby reducing powerconsumption. At this point, it is preferable that the power is turned onslightly earlier than the section having the actual required dataassigned thereto. This is to enable a tuner or a demodulator to convergein advance.

Processing Signaling Information

Meanwhile, apart from the mobile service data, the group formatter 304may also insert additional (or supplemental) information, such assignaling information providing overall (or general) system information,to the data group.

Transmission parameters associated with the transmission and receptionof broadcast signals may be determined as the signaling information. Forexample, the signaling information may include information associatedwith the RS frame (ref., Table 1 and Table 2), information associatedwith SCCC (ref., Table 3 and Table 4), information associated with theMPH frame (ref., FIG. 16A to FIG. 16C), and so on. Referring to FIG. 10Aand FIG. 10B, it is apparent that, in the data group, a signalinginformation region for inserting the signaling information is assignedto a partial region of the MPH 4 block (B4). More specifically,referring to the structure of a data group after being processed withdata interleaving, as shown in FIG. 10A, it is apparent that 6 knowndata regions are assigned to the data group in order to insert knowndata or known data place holders. Herein, the 6 known data regionsconsist of 5 regions for the purpose of training the estimation of achannel impulse response (hereinafter referred to as a “CIR”) (or thepurpose of training the channel equalizer) and 1 regions for the purposeof acquiring an initial carrier wave frequency synchronization signal.

Referring to FIG. 10A, the 1^(st), 3^(rd), 4^(th), 5^(th), and 6^(th)known data regions correspond to the known data regions assigned for theabove-described purpose of CIR estimation training or channel equalizertraining. Herein, the 1^(st) known data region and 3^(rd) to 6^(th)known data regions may each have relatively different lengths. However,a portion of each known data region has the same pattern value, and eachknown data region is inserted at equal intervals of 16 segments. In theembodiment of the present invention, the known data region is encoded by12 trellis encoders, and the status of each trellis encoder is requiredto be initialized. However, since the regions that can be initializedare pre-decided, it is inevitable to have different lengths for each ofthe 1^(st) known data region and 3^(rd) to 6^(th) known data regions.Nevertheless, once each of the known data regions is initialized, the 5known data patterns are each given the same value starting from apredetermined point to the end of each known data region. Also, each ofthe known data regions is spaced apart at equal intervals.

Meanwhile, the 2^(nd) known data region may be used for acquiring aninitial carrier wave frequency synchronization signal from the receivingsystem, or for estimating the position of a field synchronization signalor the positions of other known data regions. In order to do so, the2^(nd) known data region is configured of 2 sets of known data havingthe same pattern assigned thereto. In the present invention, theabove-described 1^(st) and 3^(rd) to 6^(th) known data regions may bereferred to as “CIR known data regions”, and the 2^(nd) known dataregion may be referred to as an “ACQ known data region”, wherein ACQstands for “acquisition”.

At this point, the data assigned to the CIR known data regions and theACQ known data region correspond to known data pre-decided based upon anagreement between the transmitting system and the receiving system.Herein, each data group maintains the same pattern. According to theembodiment of the present invention, a signaling region is assignedbetween the 1^(st) known data region and the 2^(nd) known data region.This region may also be referred to as a “signaling information region”.Herein, the data assigned to the signaling information region includesignaling information associated with the corresponding MPH frame,sub-frame, VSB frame, slot, and data group. Therefore, the data maydiffer in each data group.

Referring to FIG. 10A and FIG. 10B, the initialization data regioncorresponds to a region in which trellis memory initialization isperformed in the trellis encoding module. At this point, the signalinginformation region may be encoded at a coding rate stronger than ½ or ¼(e.g., at a coding rate of ⅙ or ⅛), thereby enhancing the receivingperformance. The information that may be inserted in the signalinginformation region includes information associated with RS frames,information associated with SCCCs, and information associated with MPHframes. More specifically, the information associated with RS frames mayinclude RS frame mode information of Table 1, and RS code modeinformation for the primary RS frame and RS code mode information forthe secondary RS frame of Table 2. Also, the signaling informationregion may be assigned with 6 bits for the information associated withthe RS frames.

The information associated with SCCCs may include SCCC block modeinformation of Table 3 and SCCC outer code mode information of Table 4.At this point, if the SCCC outer code mode information of Table 4designates a coding rate with respect to 10 MPH blocks within the datagroup, 22 bits may be assigned to the signaling information region forthe information associated with the SCCCs. However, if the SCCC outercode mode information of Table 4 designates a coding rate with respectto 4 MPH blocks within the data group, 10 bits may be assigned to thesignaling information region for the information associated with theSCCCs. In the present invention, the information associated with the RSframes and the information associated with the SCCCs may be collectivelyreferred to as an “FEC associated mode”.

Finally, the information associated with MPH frames may includesub-frame count information, slot count information, and alsoinformation on ensemble_id, SGN, NOG, and ETP. Herein, the sub-framecount information and the slot count information correspond toinformation for the synchronization of one MPH frame. The SGN and NOGinformation correspond to information for configuring an ensemble MAP(or ensemble MAP information) of the corresponding ensemble in one MPHframe. The sub-frame count information indicates a counter valuedesignating the number of each sub-frame within one MPH frame. In thepresent invention, 3 bits may be assigned to the signaling informationregion in order to indicate the sub-frame count information, and thevalue of the sub-frame count information may range from 1 to 5.Furthermore, the slot count information indicates a counter valuedesignating the number of each slot within one sub-frame. Herein, 4 bitsmay be assigned to the signaling information region in order to indicatethe slot count information, and the value of the slot count informationmay range from 1 to 16.

Moreover, service or system information may also be transmitted to thesignaling information region. Such information may be used for thepurpose of accelerating service acquisition when the power of thereceiving system is turned on, or when a broadcast service that iscurrently being viewed is changed (or switched). For example,information associated with the service included in each ensemble may betransmitted to the signaling information region. Herein, the informationassociated with the service may include service_id or major and minorchannel numbers. Additionally, a text label for each service (e.g.,short text information of FOX-TV1, WUSA-RADIO, etc.) and detailedinformation (i.e., PID or IP address or port number) on an elementarystream configuring each service may also be included in the informationassociated with the service.

When such information are transmitted from the transmitting system bymeans of the signaling information region, the receiving system maydecode the transmitted information and be informed of the types ofservices existing in the ensemble that is currently being received. Byusing such information, the receiving system may also find (or detect)the ensemble_id corresponding to the ensemble including a requested (ordesired) broadcast service. When the ensemble_id of a requestedbroadcast service is detected, the receiving system may be able toreduce power consumption by receiving only the corresponding ensemble.Herein, the above-described ensemble including the requested broadcastservice may correspond to the ensemble that was most currently received(i.e., the last received ensemble). Furthermore, when an electronicsservice guide (ESG) is transmitted to the signaling information region,the receiving system may be capable of decoding, based upon apre-decided time interval or a request, the signaling informationincluded in data groups corresponding to ensembles other than theensemble that is currently being received, thereby updating the contentsof other services that are to be broadcasted in the future.

FIG. 19( a) to FIG. 19( e) illustrate examples of a signalinginformation scenario being transmitted to the signaling informationregion according to the present invention. More specifically, FIG. 19(a) to FIG. 19( e) respectively illustrate examples of transmittingsignaling information of a current MPH frame, as well as signalinginformation of a future MPH frame, from a current MPH frame section.Referring to FIG. 19, @t represents a current point, and @t+n indicatesa point after n number of MPH frames. Herein, the value of n is decidedby an ETP, which corresponds to a cycle period for transmitting anensemble. Herein, when ETP is equal to ‘00’ (i.e., ETP=00), thisindicates that a corresponding ensemble is transmitted in each MPHframe. Therefore, n is equal to ‘1’ (i.e., n=1). Also, when ETP is equalto ‘01’ (i.e., ETP=01), this indicates that a corresponding ensemble istransmitted in each 2 MPH frames. Therefore, n is equal to ‘2’ (i.e.,n=2). Similarly, when ETP is equal to ‘10’ (i.e., ETP=10), thisindicates that a corresponding ensemble is transmitted in each 3 MPHframes. Therefore, n is equal to ‘3’ (i.e., n=3).

According to the present invention, the above-described signalinginformation may be inserted in the signaling information region of eachdata group assigned to one MPH frame and then transmitted. In this case,the signaling information of a current MPH frame or the signalinginformation of a future MPH frame may be transmitted based upon thesub-frame position. For example, since the sub-frame count informationand the slot count information respectively indicate the positioninformation corresponding to the sub-frame included in the current MPHframe and the position information corresponding to the slot included inthe current sub-frame, the sub-frame count information and the slotcount information of the current point are transmitted from allsub-frame sections.

Also, information associated with FEC, such as RS frame information, RScode information, SCCC block information, and SCCC outer codeinformation, may vary in ensemble units, and the data group of eachensemble is equally divided and assigned to 5 sub-frames. Therefore, theinformation associated with the FEC of the current point may betransmitted up to the N^(th) sub-frame (e.g., 2^(nd) sub-frame) withinan MPH frame. Then, the FEC-associated information of the next point maybe transmitted starting from the 3^(rd) sub-frame. Furthermore, ensembleMAP information, such as SGN and NOG information, may vary in ensembleunits and the data group of each ensemble is equally divided andassigned to 5 sub-frames. Therefore, the ensemble MAP information of thecurrent point may be transmitted up to the N^(th) sub-frame (e.g.,2^(nd) sub-frame) within an MPH frame. Then, the ensemble MAPinformation of the next point may be transmitted starting from the3^(rd) sub-frame. Finally, the service or system information of thecurrent point may be transmitted from all sub-frame sections.

As described above, if the information of the next point is transmittedin advance within an MPH frame, the receiving system may repeatedlyreceive in advance important transmission parameters (e.g., FEC modeinformation, ensemble MAP information, etc.) that are to be used in afuture MPH frame. Thus, the receiving system can receive correspondingensembles with more stability even when diverse interference occurs inthe channel. Furthermore, since the receiving system can extract knowndata place information, the receiving system may estimate a signalinginformation region based upon the extracted known data placeinformation. Thereafter, the receiving system may extract the signalinginformation from the estimated signaling information region and decodethe extracted signaling information, thereby using the decoded signalinginformation to recover the mobile service data.

Block Processor

FIG. 20 illustrates a block diagram showing a structure of a blockprocessor according to the present invention. Herein, the blockprocessor includes a byte-bit converter 401, a symbol encoder 402, asymbol interleaver 403, and a symbol-byte converter 404.

The byte-bit converter 401 divides the mobile service data bytes thatare inputted from the RS frame encoder 112 into bits, which are thenoutputted to the symbol encoder 402.

The byte-symbol converter 401 may also receive signaling informationincluding transmission parameters. The signaling information data bytesare also divided into bits so as to be outputted to the symbol encoder402. Herein, the signaling information including transmission parametersmay be processed with the same data processing step as that of themobile service data. More specifically, the signaling information may beinputted to the block processor 303 by passing through the datarandomizer 301 and the RS frame encoder 302. Alternatively, thesignaling information may also be directly outputted to the blockprocessor 303 without passing though the data randomizer 301 and the RSframe encoder 302.

The symbol encoder 402 corresponds to a MR/NR-rate encoder encoding theinputted data from MR bits to NR bits and outputting the data encoded atthe coding rate of MR/NR. For example, when 1 input data bit is encodedto 2 bits and then outputted, MR is equal to 1 (i.e., MR=1), and NR isequal to 2 (i.e., NR=2). And, when 1 input data bit is encoded to 4 bitsand then outputted, MR is equal to 1 (i.e., MR=1), and NR is equal to 4(i.e., NR=4). According to the embodiment of the present invention, thesymbol encoder 402 performs either a coding rate of ½ (also referred toas a ½-rate encoding process) or an encoding process at a coding rate of¼ (also referred to as a ¼-rate encoding process). The symbol encoder402 performs one of ½-rate encoding and ¼-rate encoding on the inputtedmobile service data and signaling information. Thereafter, the signalinginformation is also recognized as the mobile service data and processedaccordingly. The symbol encoder 402 may be operated as an encoder havingthe coding rate of ½ or may be operated as an encoder having the codingrate of ¼.

FIG. 21A to FIG. 21C illustrate block views showing exemplary operationsof the symbol encoder having the coding rate of ¼ according to anembodiment of the present invention. The symbol encoder of FIG. 21Aincludes a ¼ outer encoder 411, and a parallel/serial converter 412.Referring to FIG. 21A, the ¼ outer encoder 411 encodes a mobile servicedata bit U, which is being inputted to the ¼ outer encoder 411, to u0 tou3 (i.e., to 2 symbols). Then, the ¼ outer encoder 411 outputs the twoencoded symbols to the parallel/serial converter 412. Theparallel/serial converter 412 converts the two inputted symbols toserial symbol units, which are then serially outputted to the symbolinterleaver 403. More specifically, the parallel/serial converter 412outputs one symbol, which is configured of u0 and u1, to the symbolinterleaver 403. And, then the parallel/serial converter 412 outputsanother symbol, which is configured of u2 and u3, to the symbolinterleaver 403.

The symbol encoder of FIG. 21B includes a ½ outer encoder 421 and arepeater 422. Referring to FIG. 21B, the ½ outer encoder 421 encodes amobile service data bit U, which is being inputted to the ½ outerencoder 421, to u0 and u1 (i.e., to 1 symbol). Then, the ½ outer encoder421 outputs the encoded symbol to the repeater 422. The repeater 422repeats the ½-rate encoded symbol one time and outputs the repeatedsymbol to the symbol interleaver 403. More specifically, the repeater422 outputs the symbol configured of bit u0 and bit u1 to the symbolinterleaver 403. Then, the repeater 422 outputs the symbol configured ofbit u0 and bit u1 once again to the symbol interleaver 403.

The symbol encoder of FIG. 21C includes a repeater 431 and a ½ outerencoder 432. Referring to FIG. 21C, the repeater 431 repeats a mobileservice data bit U, which is being inputted to the repeater 431, so asto output two bits U and U to the ½ outer encoder 432. Thereafter, the ½outer encoder 432 encodes the mobile service data bit U being outputtedfrom the repeater 431, to u0 and u1 (i.e., to 1 symbol). Then, the ½outer encoder 431 outputs the encoded symbol to the symbol interleaver403. At this point, since identical mobile service data bits U aresequentially inputted to the ½ outer encoder 432 twice, the ½ outerencoder 432 performs the ½-rate encoding process twice on the mobileservice data bit U, which is being inputted to the repeater 431.

More specifically, when the symbol encoder 402 repeatedly outputs 2symbols encoded at a coding rate of ½, as shown in FIG. 21B, or when thesymbol encoder 402 performs the ½-rate encoding process two times on theinput data bit and then outputs the encoded data bit, as shown in FIG.21C, the overall coding rate becomes ¼. As described above, when thesymbol encoder 402 is operated as an encoder having a coding rate of ¼,the input data bit may be encoded at a coding rate of ¼, so that eachsymbol can be sequentially outputted one by one. Alternatively, theinput data may be encoded at a coding rate of ½ and then repeated onetime, so that each symbol can be sequentially outputted one by one.Furthermore, the input data bit may be encoded at a coding rate of ½ twotimes, so that each symbol can be sequentially outputted one by one.

Meanwhile, when the symbol encoder 402 is operated as an encoder havinga coding rate of ½, the input data bit is encoded at a coding rate of ½by the ½ outer encoder and then outputted. Alternatively, the input databit may also be encoded at a coding rate of ¼ by the ¼ outer encoder.Thereafter, when only one of the two symbols is selected and outputted,the symbol encoder 402 may be operated as an encoder having the codingrate of ½. In the description of the present invention, the ½-codingrate and the ¼-coding rate are merely exemplary, and the coding rate mayvary depending upon the selection of the encoded symbols or the numberof repetition of the symbols. Therefore, the present invention will notbe limited only to the examples given in the embodiments of the presentinvention. Nevertheless, if the coding rate is low, the actual amount ofdata that can be transmitted becomes smaller, accordingly. Therefore,these two factors should be accounted for when deciding the coding rate.

FIG. 22A illustrates a detailed block view of a ½ outer encoderaccording to an embodiment of the present invention. Referring to FIG.22A, the ½ outer encoder includes two delays (or a first delay and asecond delay) 501 and 503, and one adder 502. Herein, the ½ outerencoder encodes the input data bit U, so that 2 bits (i.e., u0 and u1)can be outputted. At this point, the input data bit U corresponds to anupper bit u0, which is outputted without modification and at the sametime encoded to be outputted as a lower bit u1. More specifically, theinput data bit U is directly outputted as the upper bit u0 withoutmodification and, simultaneously, outputted to the adder 502.

The adder 502 adds the input data bit U and the output of the firstdelay 501, which are then outputted to the second delay 503. Thereafter,the data that have been delayed by a set period of time (e.g., by 1clock) are outputted as the lower bit u1 and, at the same time, fed-backto the first delay 501. Subsequently, the first delay 501 delays datafed-back by from the second delay 503 by a set period of time (e.g., by1 clock). Then, the delayed data are outputted to the adder 502. At thispoint, if the data bit U being inputted to the symbol encoder 402corresponds to a data bit that is to be encoded at a coding rate of ¼, asymbol configured of u0u1 bits may be repeated twice and then outputted.Alternatively, the input data bit U may be repeated once, which is theninputted to the ½ outer encoder of FIG. 22A.

FIG. 22B illustrates a detailed block view of a ¼ outer encoderaccording to an embodiment of the present invention. Referring to FIG.22B, the ¼ outer encoder includes two delays (or a first delay and asecond delay) 501 and 503, and three adders 502, 504, and 505. Herein,the ¼ outer encoder encodes the input data bit U, so that 4 bits (i.e.,u0 to u3) can be outputted. At this point, the input data bit Ucorresponds to an uppermost bit u0, which is outputted withoutmodification and at the same time encoded to be outputted as lower bitu1u2u3. More specifically, the input data bit U is directly outputted asthe uppermost bit u0 and simultaneously outputted to the first and thirdadders 502 and 505. The first adder 502 adds the input data bit U andthe output bit of the first delay unit 501 and, then, outputs the addedbit to the second delay unit 503. Then, the data bit delayed by apre-determined time (e.g., by 1 clock) in the second delay unit 503 isoutputted as lower bit u1 and simultaneously fed-back to the first delayunit 501. The first delay unit 501 delays the data bit fed-back from thesecond delay unit 503 by a pre-determined time (e.g., by 1 clock). Then,the first delay unit 501 outputs the delayed data bit to the first adder502 and the second adder 504. The second adder 504 adds the data bitsoutputted from the first and second delay units 501 and 503 as a lowerbit u2. The third adder 505 adds the input data bit U and the output ofthe second delay unit 503 and outputs the added data bit as a lower bitu3.

At this point, if the input data bit U corresponds to data encoded at a½-coding rate, the symbol encoder 402 configures a symbol with u0u1 bitsfrom the 4 output bits u0u1u2u3. Then, the symbol encoder 402 outputsthe newly configured symbol. Alternatively, if the input data bit Ucorresponds to data encoded at a ¼-coding rate, the symbol encoder 402configures and outputs a symbol with bits u0u1 and, then, configures andoutputs another symbol with bits u2u3. According to another embodimentof the present invention, if the input data bit U corresponds to dataencoded at a ¼-coding rate, the symbol encoder 402 may also configureand output a symbol with bits u0u1, and then repeat the process onceagain and output the corresponding bits.

According to yet another embodiment of the present invention, the symbolencoder outputs all four output bits U u0u1u2u3. Then, when using the½-coding rate, the symbol interleaver 403 located behind the symbolencoder 402 selects only the symbol configured of bits u0u1 from thefour output bits u0u1u2u3. Alternatively, when using the ¼-coding rate,the symbol interleaver 403 may select the symbol configured of bits u0u1and then select another symbol configured of bits u2u3. According toanother embodiment, when using the ¼-coding rate, the symbol interleaver403 may repeatedly select the symbol configured of bits u0u1.

The output of the symbol encoder 402 is inputted to the symbolinterleaver 403. Then, the symbol interleaver 403 performs blockinterleaving in symbol units on the data outputted from the symbolencoder 402. Any interleaver performing structural rearrangement (orrealignment) may be applied as the symbol interleaver 403 of the blockprocessor. However, in the present invention, a variable length symbolinterleaver that can be applied even when a plurality of lengths isprovided for the symbol, so that its order may be rearranged, may alsobe used.

FIG. 23( a) to FIG. 23( c) illustrate a symbol interleaver according toan embodiment of the present invention. Herein, the symbol interleaveraccording to the embodiment of the present invention corresponds to avariable length symbol interleaver that may be applied even when aplurality of lengths is provided for the symbol, so that its order maybe rearranged. Particularly, FIG. 23( a) to FIG. 23( c) illustrate anexample of the symbol interleaver when BK=6 and BL=8. Herein, BKindicates a number of symbols that are outputted for symbol interleavingfrom the symbol encoder 402. And, BL represents a number of symbols thatare actually interleaved by the symbol interleaver 403.

In the present invention, the symbol intereleaver 403 should satisfy theconditions of BL=2^(n) (wherein n is an integer) and of BL≧BK. If thereis a difference in value between BK and BL, (BL-BK) number of null (ordummy) symbols is added, thereby creating an interleaving pattern.Therefore, BK becomes a block size of the actual symbols that areinputted to the symbol interleaver 403 in order to be interleaved. BLbecomes an interleaving unit when the interleaving process is performedby an interleaving pattern created from the symbol interleaver 403.

The example of what is described above is illustrated in FIG. 23( a) toFIG. 23( c). The number of symbols outputted from the symbol encoder 402in order to be interleaved is equal to 6 (i.e., BK=6). In other words, 6symbols are outputted from the symbol encoder 402 in order to beinterleaved. And, the actual interleaving unit (BL) is equal to 8symbols. Therefore, as shown in FIG. 23( a), 2 symbols are added to thenull (or dummy) symbol, thereby creating the interleaving pattern.Equation 4 shown below described the process of sequentially receivingBK number of symbols, the order of which is to be rearranged, andobtaining an BL value satisfying the conditions of BL=2^(n) (wherein nis an integer) and of BL≧BK, thereby creating the interleaving so as torealign (or rearrange) the symbol order.

In relation to all places, wherein 0≦i≦BL−1,

P(i)={S×i×(i+1)/2} mod BL  Equation 5

Herein, BL≧BK, BL=2^(n), and n and S are integers. FIG. 23 shows anexample of an interleaving pattern and an interleaving process, whereinit is assumed that S is equal to 89, and that BL is equal to 8. As shownin FIG. 23( b), the order of BK number of input symbols and (BL-BK)number of null symbols is rearranged by using the above-mentionedEquation 4. Then, as shown in FIG. 23( c), the null byte places areremoved, so as to rearrange the order, by using Equation 5 shown below.Thereafter, the symbol that is interleaved by the rearranged order isthen outputted to the symbol-byte converter.

if P(i)>BK−1, then P(i) place is removed and rearranged  Equation 6

Subsequently, the symbol-byte converter 404 converts to bytes the mobileservice data symbols, having the rearranging of the symbol ordercompleted and then outputted in accordance with the rearranged orderfrom the symbol interleaver 403, and thereafter outputs the convertedbytes to the group formatter 304.

FIG. 24A illustrates a block diagram showing the structure of a blockprocessor according to another embodiment of the present invention.Herein, the block processor includes an interleaving unit 610 and ablock formatter 620. The interleaving unit 610 may include a byte-symbolconverter 611, a symbol-byte converter 612, a symbol interleaver 613,and a symbol-byte converter 614. Herein, the symbol interleaver 613 mayalso be referred to as a block interleaver.

The byte-symbol converter 611 of the interleaving unit 610 converts themobile service data X outputted in byte units from the RS frame encoder302 to symbol units. Then, the byte-symbol converter 611 outputs theconverted mobile service data symbols to the symbol-byte converter 612and the symbol interleaver 613. More specifically, the byte-symbolconverter 611 converts each 2 bits of the inputted mobile service databyte (=8 bits) to 1 symbol and outputs the converted symbols. This isbecause the input data of the trellis encoding module 256 consist ofsymbol units configured of 2 bits. The relationship between the blockprocessor 303 and the trellis encoding module 256 will be described indetail in a later process. At this point, the byte-symbol converter 611may also receive signaling information including transmissionparameters. Furthermore, the signaling information bytes may also bedivided into symbol units and then outputted to the symbol-byteconverter 612 and the symbol interleaver 613.

The symbol-byte converter 612 groups 4 symbols outputted from thebyte-symbol converter 611 so as to configure a byte. Thereafter, theconverted data bytes are outputted to the block formatter 620. Herein,each of the symbol-byte converter 612 and the byte-symbol converter 611respectively performs an inverse process of one another. Therefore, theyields (or results) of these two blocks are offset. Accordingly, asshown in FIG. 24B, the input data X bypass the byte-symbol converter 611and the symbol-byte converter 612 and are directly inputted to the blockformatter 620. More specifically, the interleaving unit 610 of FIG. 24Bhas a structure equivalent to that of the interleaving unit shown inFIG. 24A. Therefore, the same reference numerals will be used in FIG.24A and FIG. 24B.

The symbol interleaver 613 performs block interleaving in symbol unitson the data that are outputted from the byte-symbol converter 611.Subsequently, the symbol interleaver 613 outputs the interleaved data tothe symbol-byte converter 614. Herein, any type of interleaver that canrearrange the structural order may be used as the symbol interleaver 613of the present invention. In the example given in the present invention,a variable length interleaver that may be applied for symbols having awide range of lengths, the order of which is to be rearranged. Forexample, the symbol interleaver of FIG. 23 may also be used in the blockprocessor shown in FIG. 24A and FIG. 24B.

The symbol-byte converter 614 outputs the symbols having the rearrangingof the symbol order completed by the symbol interleaver 613, inaccordance with the rearranged order. Thereafter, the symbols aregrouped to be configured in byte units, which are then outputted to theblock formatter 620. More specifically, the symbol-byte converter 614groups 4 symbols outputted from the symbol interleaver 613 so as toconfigure a data byte. As shown in FIG. 25, the block formatter 620performs the process of aligning the output of each symbol-byteconverter 612 and 614 within the block in accordance with a setstandard. Herein, the block formatter 620 operates in association withthe trellis encoding module 256.

More specifically, the block formatter 620 decides the output order ofthe mobile service data outputted from each symbol-byte converter 612and 614 while taking into consideration the place (or order) of the dataexcluding the mobile service data that are being inputted, wherein themobile service data include main service data, known data, RS paritydata, and MPEG header data.

According to the embodiment of the present invention, the trellisencoding module 256 is provided with 12 trellis encoders. FIG. 26illustrates a block diagram showing the trellis encoding module 256according to the present invention. In the example shown in FIG. 26, 12identical trellis encoders are combined to the interleaver in order todisperse noise. Herein, each trellis encoder may be provided with apre-coder.

FIG. 27A illustrates the block processor 303 being concatenated with thetrellis encoding module 256. In the transmitting system, a plurality ofblocks actually exists between the pre-processor 230 including the blockprocessor and the trellis encoding module 256, as shown in FIG. 5.Conversely, the receiving system considers the pre-processor to beconcatenated with the trellis encoding module 256, thereby performingthe decoding process accordingly. However, the data excluding the mobileservice data that are being inputted to the trellis encoding module 256,wherein the mobile service data include main service data, known data,RS parity data, and MPEG header data, correspond to data that are addedto the blocks existing between the block processor and the trellisencoding module 256. FIG. 27B illustrates an example of a data processor650 being positioned between the block processor 303 and the trellisencoding module 256, while taking the above-described instance intoconsideration.

Herein, when the interleaving unit 610 of the block processor 303performs a ½-rate encoding process, the interleaving unit 610 may beconfigured as shown in FIG. 24A (or FIG. 24B). Referring to FIG. 5, forexample, the data processor 650 may include a group formatter 304, adata deinterleaver 305, a packet formatter 306, and a packet multiplexer240, and a data randomizer 251, a RS encoder/non-systematic RS encoder252, a data interleaver 253, a parity replacer 254, and a non-systematicRS encoder 255 of a post-processor 250.

At this point, the trellis encoding module 256 symbolizes the data thatare being inputted so as to divide the symbolized data and to send thedivided data to each trellis encoder in accordance with a pre-definedmethod. Herein, one byte is converted into 4 symbols, each beingconfigured of 2 bits. Also, the symbols created from the single databyte are all transmitted to the same trellis encoder. Accordingly, eachtrellis encoder pre-codes an upper bit of the input symbol, which isthen outputted as the uppermost output bit C2. Alternatively, eachtrellis encoder trellis-encodes a lower bit of the input symbol, whichis then outputted as two output bits C1 and C0. The block formatter 620is controlled so that the data byte outputted from each symbol-byteconverter can be transmitted to different trellis encoders.

Hereinafter, the operation of the block formatter 620 will now bedescribed in detail with reference to FIG. 20 to FIG. 24. Referring toFIG. 24A, for example, the data byte outputted from the symbol-byteconverter 612 and the data byte outputted from the symbol-byte converter614 are inputted to different trellis encoders of the trellis encodingmodule 256 in accordance with the control of the block formatter 620.Hereinafter, the data byte outputted from the symbol-byte converter 612will be referred to as X, and the data byte outputted from thesymbol-byte converter 614 will be referred to as Y, for simplicity.Referring to FIG. 25( a), each number (i.e., 0 to 11) indicates thefirst to twelfth trellis encoders of the trellis encoding module 256,respectively.

In addition, the output order of both symbol-byte converters arearranged (or aligned) so that the data bytes outputted from thesymbol-byte converter 612 are respectively inputted to the 0^(th) to5^(th) trellis encoders (0 to 5) of the trellis encoding module 256, andthat the data bytes outputted from the symbol-byte converter 614 arerespectively inputted to the 6^(th) to 11^(th) trellis encoders (6 to11) of the trellis encoding module 256. Herein, the trellis encodershaving the data bytes outputted from the symbol-byte converter 612allocated therein, and the trellis encoders having the data bytesoutputted from the symbol-byte converter 614 allocated therein aremerely examples given to simplify the understanding of the presentinvention. Furthermore, according to an embodiment of the presentinvention, and assuming that the input data of the block processor 303correspond to a block configured of 12 bytes, the symbol-byte converter612 outputs 12 data bytes from X0 to X1, and the symbol-byte converter614 outputs 12 data bytes from Y0 to Y11.

FIG. 25( b) illustrates an example of data being inputted to the trellisencoding module 256. Particularly, FIG. 25( b) illustrates an example ofnot only the mobile service data but also the main service data and RSparity data being inputted to the trellis encoding module 256, so as tobe distributed to each trellis encoder. More specifically, the mobileservice data outputted from the block processor 303 pass through thegroup formatter 304, from which the mobile service data are mixed withthe main service data and RS parity data and then outputted, as shown inFIG. 25( a). Accordingly, each data byte is respectively inputted to the12 trellis encoders in accordance with the positions (or places) withinthe data group after being data-interleaved.

Herein, when the output data bytes X and Y of the symbol-byte converters612 and 614 are assigned to each respective trellis encoder, the inputof each trellis encoder may be configured as shown in FIG. 25( b). Morespecifically, referring to FIG. 25( b), the six mobile service databytes (X0 to X5) outputted from the symbol-byte converter 612 aresequentially assigned (or distributed) to the first to sixth trellisencoders (0 to 5) of the trellis encoding module 256. Also, the 2 mobileservice data bytes Y0 and Y1 outputted from the symbol-byte converter614 are sequentially assigned to the 7^(th) and 8^(th) trellis encoders(6 and 7) of the trellis encoding module 256. Thereafter, among the 5main service data bytes, 4 data bytes are sequentially assigned to the9^(th) and 12^(th) trellis encoders (8 to 11) of the trellis encodingmodule 256. Finally, the remaining 1 byte of the main service data byteis assigned once again to the first trellis encoder (0).

It is assumed that the mobile service data, the main service data, andthe RS parity data are assigned to each trellis encoder, as shown inFIG. 25( b). It is also assumed that, as described above, the input ofthe block processor 303 is configured of 12 bytes, and that 12 bytesfrom X0 to X1 are outputted from the symbol-byte converter 612, and that12 bytes from Y0 to Y11 are outputted from the symbol-byte converter614. In this case, as shown in FIG. 25( c), the block formatter 620arranges the data bytes that are to be outputted from the symbol-byteconverters 612 and 614 by the order of X0 to X5, Y0, Y1, X6 to X10, Y2to Y7, X11, and Y8 to Y11. More specifically, the trellis encoder thatis to perform the encoding process is decided based upon the position(or place) within the transmission frame in which each data byte isinserted. At this point, not only the mobile service data but also themain service data, the MPEG header data, and the RS parity data are alsoinputted to the trellis encoding module 256. Herein, it is assumed that,in order to perform the above-described operation, the block formatter620 is informed of (or knows) the information on the data group formatafter the data-interleaving process.

FIG. 28 illustrates a block diagram of the block processor performing anencoding process at a coding rate of 1/N according to an embodiment ofthe present invention. Herein, the block processor includes (N−1) numberof symbol interleavers 741 to 74N-1, which are configured in a parallelstructure. More specifically, the block processor having the coding rateof 1/N consists of a total of N number of branches (or paths) includinga branch (or path), which is directly transmitted to the block formatter730. In addition, the symbol interleaver 741 to 74N-1 of each branch mayeach be configured of a different symbol interleaver. Furthermore, (N−1)number of symbol-byte converter 751 to 75N-1 each corresponding to each(N−1) number of symbol interleavers 741 to 74N-1 may be included at theend of each symbol interleaver, respectively. Herein, the output data ofthe (N−1) number of symbol-byte converter 751 to 75N-1 are also inputtedto the block formatter 730.

In the example of the present invention, N is equal to or smaller than12. If N is equal to 12, the block formatter 730 may align the outputdata so that the output byte of the 12^(th) symbol-byte converter 75N-1is inputted to the 12^(th) trellis encoder. Alternatively, if N is equalto 3, the block formatter 730 may arrange the output order, so that thedata bytes outputted from the symbol-byte converter 720 are inputted tothe 1^(st) to 4^(th) trellis encoders of the trellis encoding module256, and that the data bytes outputted from the symbol-byte converter751 are inputted to the 5^(th) to 8^(th) trellis encoders, and that thedata bytes outputted from the symbol-byte converter 752 are inputted tothe 9^(th) to 12^(th) trellis encoders. At this point, the order of thedata bytes outputted from each symbol-byte converter may vary inaccordance with the position within the data group of the data otherthan the mobile service data, which are mixed with the mobile servicedata that are outputted from each symbol-byte converter.

The number of trellis encoders, the number of symbol-byte converters,and the number of symbol interleavers proposed in the present inventionare merely exemplary. And, therefore, the corresponding numbers do notlimit the spirit or scope of the present invention. It is apparent tothose skilled in the art that the type and position of each data bytebeing allocated to each trellis encoder of the trellis encoding module256 may vary in accordance with the data group format. Therefore, thepresent invention should not be understood merely by the examples givenin the description set forth herein.

The mobile service data that are encoded at a coding rate of MR/RN andoutputted from the block processor 303 are inputted to the groupformatter 304. Herein, in the example of the present invention, theorder of the output data outputted from the block formatter of the blockprocessor 303 are aligned and outputted in accordance with the positionof the data bytes within the data group.

Demodulating Unit within Receiving System

FIG. 29 illustrates an example of a demodulating unit in a digitalbroadcast receiving system according to the present invention. Thedemodulating unit of FIG. 29 uses known data information, which isinserted in the mobile service data section and, then, transmitted bythe transmitting system, so as to perform carrier synchronizationrecovery, frame synchronization recovery, and channel equalization,thereby enhancing the receiving performance. Also the demodulating unitmay turn the power on only during a slot to which the data group of thedesignated (or desired) ensemble is assigned, thereby reducing powerconsumption of the receiving system.

Referring to FIG. 29, the demodulating unit includes a demodulator 1002,an equalizer 1003, a known sequence detector 1004, a block decoder 1005,a RS frame decoder 1006, a derandomizer 1007. The demodulating unit mayfurther include a data deinterleaver 1009, a RS decoder 1010, and a dataderandomizer 1011. The demodulating unit may further include a signalinginformation decoder 1013. The receiving system also may further includea power controller 5000 for controlling power supply of the demodulatingunit.

Herein, for simplicity of the description of the present invention, theRS frame decoder 1006, and the derandomizer 1007 will be collectivelyreferred to as a mobile service data processing unit. And, the datadeinterleaver 1009, the RS decoder 1010, and the data derandomizer 1011will be collectively referred to as a main service data processing unit.More specifically, a frequency of a particular channel tuned by a tunerdown converts to an intermediate frequency (IF) signal. Then, thedown-converted data 1001 outputs the down-converted IF signal to thedemodulator 1002 and the known sequence detector 1004. At this point,the down-converted data 1001 is inputted to the demodulator 1002 and theknown sequence detector 1004 via analog/digital converter ADC (notshown). The ADC converts pass-band analog IF signal into pass-banddigital IF signal.

The demodulator 1002 performs self gain control, carrier recovery, andtiming recovery processes on the inputted pass-band digital IF signal,thereby modifying the IF signal to a base-band signal. Then, thedemodulator 1002 outputs the newly created base-band signal to theequalizer 1003 and the known sequence detector 1004. The equalizer 1003compensates the distortion of the channel included in the demodulatedsignal and then outputs the error-compensated signal to the blockdecoder 1005.

At this point, the known sequence detector 1004 detects the knownsequence place inserted by the transmitting end from the input/outputdata of the demodulator 1002 (i.e., the data prior to the demodulationprocess or the data after the demodulation process). Thereafter, theplace information along with the symbol sequence of the known data,which are generated from the detected place, is outputted to thedemodulator 1002 and the equalizer 1003. Also, the known data detector1004 outputs a set of information to the block decoder 1005. This set ofinformation is used to allow the block decoder 1005 of the receivingsystem to identify the mobile service data that are processed withadditional encoding from the transmitting system and the main servicedata that are not processed with additional encoding. In addition,although the connection status is not shown in FIG. 29, the informationdetected from the known data detector 1004 may be used throughout theentire receiving system and may also be used in the RS frame decoder1006.

The demodulator 1002 uses the known data symbol sequence during thetiming and/or carrier recovery, thereby enhancing the demodulatingperformance. Similarly, the equalizer 1003 uses the known data so as toenhance the equalizing performance. Moreover, the decoding result of theblock decoder 1005 may be fed-back to the equalizer 1003, therebyenhancing the equalizing performance.

Power On/Off Control

The data demodulated in the demodulator 1002 or the data equalized inthe channel equalizer 1003 is inputted to the signaling informationdecoder 1013. The known data information detected in the known sequencedetector 1004 is inputted to the signaling information decoder 1013.

The signaling information decoder 1013 extracts and decodes signalinginformation from the inputted data, the decoded signaling informationprovides to blocks requiring the signaling information. For example, theSCCC-associated information may output to the block decoder 1005, andthe RS frame-associated information may output to the RS frame decoder1006. The MPH frame-associated information may output to the knownsequence detector 1004 and the power controller 5000.

Herein, the RS frame-associated information may include RS frame modeinformation and RS code mode information. The SCCC-associatedinformation may include SCCC block mode information and SCCC outer codemode information. The MPH frame-associated information may includesub-frame count information, slot count information, ensemble_idinformation, SGN information, NoG information, ETP information and soon, as shown in FIG. 18.

More specifically, the signaling information between first known dataarea and second known data area can know by using known data informationbeing outputted in the known sequence detector 1004. Therefore, thesignaling information decoder 1013 may extract and decode signalinginformation from the data being outputted in the demodulator 1002 or thechannel equalizer 1003.

The power controller 5000 is inputted the MPH frame-associatedinformation from the signaling information decoder 1013, and controlspower of the tuner and the demodulating unit.

According to the embodiment of the present invention, the powercontroller 5000 turns the power on only during a slot to which a slot ofthe ensemble including user-selected mobile service is assigned. Thepower controller 5000 then turns the power off during the remainingslots.

For example, it is assumed that data groups of a 1^(st) ensemble withNOG=3, a 2^(nd) ensemble with NOG=4 are assigned to one MPH frame, asshown in FIG. 17( a). It is also assumed that the user has selected amobile service included in the 1^(st) ensemble using the keypad providedon the remote controller or terminal. In this case, the power controller5000 turns the power on only during a slot that data groups of the1^(st) ensemble is assigned, as shown in FIG. 17( b), and turns thepower off during the remaining slots, thereby reducing powerconsumption.

Demodulator and Known Sequence Detector

At this point, the transmitting system may transmit known dataperiodically inserted within data frame, as shown in FIG. 10A.

FIG. 30 illustrates an example of known data sequence being periodicallyinserted and transmitted in-between actual data by the transmittingsystem. Referring to FIG. 30, AS represents the number of valid datasymbols, and BS represents the number of known data symbols. Therefore,BS number of known data symbols are inserted and transmitted at a periodof (AS+BS) symbols. Herein, AS may correspond to mobile service data,main service data, or a combination of mobile service data and mainservice data. In order to be differentiated from the known data, datacorresponding to AS will hereinafter be referred to as valid data.

Referring to FIG. 30, known data sequence having the same pattern areincluded in each known data section that is being periodically inserted.Herein, the length of the known data sequence having identical datapatterns may be either equal to or different from the length of theentire (or total) known data sequence of the corresponding known datasection (or block). If the two lengths are different from one another,the length of the entire known data sequence should be longer than thelength of the known data sequence having identical data patterns. Inthis case, the same known data sequences are included in the entireknown data sequence. The known sequence detector 1004 detects theposition of the known data being periodically inserted and transmittedas described above. At the same time, the known sequence detector 1004may also estimate initial frequency offset during the process ofdetecting known data. In this case, the demodulator 1002 may estimatewith more accuracy carrier frequency offset from the information on theknown data position (or known sequence position indicator) and initialfrequency offset estimation value, thereby compensating the estimatedinitial frequency offset.

FIG. 31 illustrates a detailed block diagram of a demodulator accordingto the present invention. Referring to FIG. 31, the demodulator includesa phase splitter 1010, a numerically controlled oscillator (NCO) 1020, afirst multiplier 1030, a resampler 1040, a second multiplier 1050, amatched filter 1060, a DC remover 1070, a timing recovery unit 1080, acarrier recovery unit 1090, and a phase compensator 1110. Herein, theknown sequence detector 1004 includes a known sequence detector andinitial frequency offset estimator 1004-1 for estimating known datainformation and initial frequency offset. Also referring to FIG. 31, thephase splitter 1010 receives a pass band digital signal and splits thereceived signal into a pass band digital signal of a real number elementand a pass band digital signal of an imaginary number element bothhaving a phase of 90 degrees between one another. In other words, thepass band digital signal is split into complex signals. The splitportions of the pass band digital signal are then outputted to the firstmultiplier 1030. Herein, the real number signal outputted from the phasesplitter 1010 will be referred to as an ‘I’ signal, and the imaginarynumber signal outputted from the phase splitter 1010 will be referred toas a ‘Q’ signal, for simplicity of the description of the presentinvention.

The first multiplier 1030 multiplies the I and Q pass band digitalsignals, which are outputted from the phase splitter 1010, to a complexsignal having a frequency proportional to a constant being outputtedfrom the NCO 1020, thereby changing the I and Q pass band digitalsignals to baseband digital complex signals. Then, the baseband digitalsignals of the first multiplier 1030 are inputted to the resampler 1040.The resampler 1040 resamples the signals being outputted from the firstmultiplier 1030 so that the signal corresponds to the timing clockprovided by the timing recovery unit 1080. Thereafter, the resampler1040 outputs the resampled signals to the second multiplier 1050.

For example, when the analog/digital converter uses a 25 MHz fixedoscillator, the baseband digital signal having a frequency of 25 MHz,which is created by passing through the analog/digital converter, thephase splitter 1010, and the first multiplier 1030, is processed with aninterpolation process by the resampler 1040. Thus, the interpolatedsignal is recovered to a baseband digital signal having a frequencytwice that of the receiving signal of a symbol clock (i.e., a frequencyof 21.524476 MHz). Alternatively, if the analog/digital converter usesthe timing clock of the timing recovery unit 1080 as the samplingfrequency (i.e., if the analog/digital converter uses a variablefrequency) in order to perform an A/D conversion process, the resampler1040 is not required and may be omitted.

The second multiplier 1050 multiplies an output frequency of the carrierrecovery unit 1090 with the output of the resampler 1040 so as tocompensate any remaining carrier included in the output signal of theresampler 1040. Thereafter, the compensated carrier is outputted to thematched filter 1060 and the timing recovery unit 1080. The signalmatched-filtered by the matched filter 1060 is inputted to the DCremover 1070, the known sequence detector and initial frequency offsetestimator 1004-1, and the carrier recovery unit 1090.

The known sequence detector and initial frequency offset estimator1004-1 detects the place (or position) of the known data sequences thatare being periodically or non-periodically transmitted. Simultaneously,the known sequence detector and initial frequency offset estimator1004-1 estimates an initial frequency offset during the known sequencedetection process. More specifically, while the transmission data frameis being received, as shown in FIG. 10A, the known sequence detector andinitial frequency offset estimator 1004-1 detects the position (orplace) of the known data included in the transmission data frame. Then,the known sequence detector and initial frequency offset estimator1004-1 outputs the detected information on the known data place (i.e., aknown sequence position indicator) to the timing recovery unit 1080, thecarrier recovery unit 1090, and the phase compensator 1110 of thedemodulator 1002 and the equalizer 1003. Furthermore, the known sequencedetector and initial frequency offset estimator 1004-1 estimates theinitial frequency offset, which is then outputted to the carrierrecovery unit 1090. At this point, the known sequence detector andinitial frequency offset estimator 1004-1 may either receive the outputof the matched filter 1060 or receive the output of the resampler 1040.This may be optionally decided depending upon the design of the systemdesigner.

The timing recovery unit 1080 uses the output of the second multiplier1050 and the known sequence position indicator detected from the knownsequence detector and initial frequency offset estimator 1004-1, so asto detect the timing error and, then, to output a sampling clock beingin proportion with the detected timing error to the resampler 1040,thereby adjusting the sampling timing of the resampler 1040. At thispoint, the timing recovery unit 1080 may receive the output of thematched filter 1060 instead of the output of the second multiplier 1050.This may also be optionally decided depending upon the design of thesystem designer.

Meanwhile, the DC remover 1070 removes a pilot tone signal (i.e., DCsignal), which has been inserted by the transmitting system, from thematched-filtered signal. Thereafter, the DC remover 1070 outputs theprocessed signal to the phase compensator 1110. The phase compensator1110 uses the data having the DC removed by the DC remover 1070 and theknown sequence position indicator detected by the known sequencedetector and initial frequency offset estimator 1004-1 to estimate thefrequency offset and, then, to compensate the phase change included inthe output of the DC remover 1070. The data having its phase changecompensated are inputted to the equalizer 1003. Herein, the phasecompensator 1110 is optional. If the phase compensator 1110 is notprovided, then the output of the DC remover 1070 is inputted to theequalizer 1003 instead.

FIG. 32 includes detailed block diagrams of the timing recovery unit1080, the carrier recovery unit 1090, and the phase compensator 1110 ofthe demodulator. According to an embodiment of the present invention,the carrier recovery unit 1090 includes a buffer 1091, a frequencyoffset estimator 1092, a loop filter 1093, a holder 1094, an adder 1095,and a NCO 1096. Herein, a decimator may be included before the buffer1091. The timing recovery unit 1080 includes a decimator 1081, a buffer1082, a timing error detector 1083, a loop filter 1084, a holder 1085,and a NCO 1086. Finally, the phase compensator 1110 includes a buffer1111, a frequency offset estimator 1112, a holder 1113, a NCO 1114, anda multiplier 1115. Furthermore, a decimator 1200 may be included betweenthe phase compensator 1110 and the equalizer 1003. The decimator 1200may be outputted in front of the DC remover 1070 instead of at theoutputting end of the phase compensator 1110.

Herein, the decimators correspond to components required when a signalbeing inputted to the demodulator is oversampled to N times by theanalog/digital converter. More specifically, the integer N representsthe sampling rate of the received signal. For example, when the inputsignal is oversampled to 2 times (i.e., when N=2) by the analog/digitalconverter, this indicates that two samples are included in one symbol.In this case, each of the decimators corresponds to a ½ decimator.Depending upon whether or not the oversampling process of the receivedsignal has been performed, the signal may bypass the decimators.

Meanwhile, the output of the second multiplier 1050 is temporarilystored in the decimator 1081 and the buffer 1082 both included in thetiming recovery unit 1080. Subsequently, the temporarily stored outputdata are inputted to the timing error detector 1083 through thedecimator 1081 and the buffer 1082. Assuming that the output of thesecond multiplier 1050 is oversampled to N times its initial state, thedecimator 1081 decimates the output of the second multiplier 1050 at adecimation rate of 1/N. Then, the 1/N-decimated data are inputted to thebuffer 1082. In other words, the decimator 1081 performs decimation onthe input signal in accordance with a VSB symbol cycle. Furthermore, thedecimator 1081 may also receive the output of the matched filter 1060instead of the output of the second multiplier 1050. The timing errordetector 1083 uses the data prior to or after being processed withmatched-filtering and the known sequence position indicator outputtedfrom the known sequence detector and initial frequency offset estimator1004-1 in order to detect a timing error. Thereafter, the detectedtiming error is outputted to the loop filter 1084. Accordingly, thedetected timing error information is obtained once during eachrepetition cycle of the known data sequence.

For example, if a known data sequence having the same pattern isperiodically inserted and transmitted, as shown in FIG. 30, the timingerror detector 1083 may use the known data in order to detect the timingerror. There exists a plurality of methods for detecting timing error byusing the known data. In the example of the present invention, thetiming error may be detected by using a correlation characteristicbetween the known data and the received data in the time domain, theknown data being already known in accordance with a pre-arrangedagreement between the transmitting system and the receiving system. Thetiming error may also be detected by using the correlationcharacteristic of the two known data types being received in thefrequency domain. Thus, the detected timing error is outputted. Inanother example, a spectral lining method may be applied in order todetect the timing error. Herein, the spectral lining method correspondsto a method of detecting timing error by using sidebands of the spectrumincluded in the received signal.

The loop filter 1084 filters the timing error detected by the timingerror detector 1083 and, then, outputs the filtered timing error to theholder 1085. The holder 1085 holds (or maintains) the timing errorfiltered and outputted from the loop filter 1084 during a pre-determinedknown data sequence cycle period and outputs the processed timing errorto the NCO 1086. Herein, the order of positioning of the loop filter1084 and the holder 1085 may be switched with one another. Inadditionally, the function of the holder 1085 may be included in theloop filter 1084, and, accordingly, the holder 1085 may be omitted. TheNCO 1086 accumulates the timing error outputted from the holder 1085.Thereafter, the NCO 1086 outputs the phase element (i.e., a samplingclock) of the accumulated timing error to the resampler 1040, therebyadjusting the sampling timing of the resampler 1040.

Meanwhile, the buffer 1091 of the carrier recovery unit 1090 may receiveeither the data inputted to the matched filter 1060 or the dataoutputted from the matched filter 1060 and, then, temporarily store thereceived data. Thereafter, the temporarily stored data are outputted tothe frequency offset estimator 1092. If a decimator is provided in frontof the buffer 1091, the input data or output data of the matched filter1060 are decimated by the decimator at a decimation rate of 1/N.Thereafter, the decimated data are outputted to the buffer 1091. Forexample, when the input data or output data of the matched filter 1060are oversampled to 2 times (i.e., when N=2), this indicates that theinput data or output data of the matched filter 1060 are decimated at arate of ½ by the decimator 1081 and then outputted to the buffer 1091.More specifically, when a decimator is provided in front of the buffer1091, the carrier recovery unit 1090 operates in symbol units.Alternatively, if a decimator is not provided, the carrier recovery unit1090 operates in oversampling units.

The frequency offset estimator 1092 uses the input data or output dataof the matched filter 1060 and the known sequence position indicatoroutputted from the known sequence detector and initial frequency offsetestimator 1004-1 in order to estimate the frequency offset. Then, theestimated frequency offset is outputted to the loop filter 1093.Therefore, the estimated frequency offset value is obtained once everyrepetition period of the known data sequence. The loop filter 1093performs low pass filtering on the frequency offset value estimated bythe frequency offset estimator 1092 and outputs the low pass-filteredfrequency offset value to the holder 1094. The holder 1094 holds (ormaintains) the low pass-filtered frequency offset value during apre-determined known data sequence cycle period and outputs thefrequency offset value to the adder 1095. Herein, the positions of theloop filter 1093 and the holder 1094 may be switched from one to theother. Furthermore, the function of the holder 1085 may be included inthe loop filter 1093, and, accordingly, the holder 1094 may be omitted.

The adder 1095 adds the value of the initial frequency offset estimatedby the known sequence detector and initial frequency offset estimator1004-1 to the frequency offset value outputted from the loop filter 1093(or the holder 1094). Thereafter, the added offset value is outputted tothe NCO 1096. Herein, if the adder 1095 is designed to also receive theconstant being inputted to the NCO 1020, the NCO 1020 and the firstmultiplier 1030 may be omitted. In this case, the second multiplier 1050may simultaneously perform changing signals to baseband signals andremoving remaining carrier.

The NCO 1096 generates a complex signal corresponding to the frequencyoffset outputted from the adder 1095, which is then outputted to thesecond multiplier 1050. Herein, the NCO 1096 may include a ROM. In thiscase, the NCO 1096 generates a compensation frequency corresponding tothe frequency offset being outputted from the adder 1095. Then, the NCO1096 reads a complex cosine corresponding to the compensation frequencyfrom the ROM, which is then outputted to the second multiplier 1050. Thesecond multiplier 1050 multiplies the output of the NCO 1094 included inthe carrier recovery unit 1090 to the output of the resampler 1040, soas to remove the carrier offset included in the output signal of theresampler 1040.

FIG. 33 illustrates a detailed block diagram of the frequency offsetestimator 1092 of the carrier recovery unit 1090 according to anembodiment of the present invention. Herein, the frequency offsetestimator 1092 operates in accordance with the known sequence positionindicator detected from the known sequence detector and initialfrequency offset estimator 1004-1. At this point, if the input data oroutput data of the matched filter 1060 are inputted through thedecimator, the frequency offset estimator 1092 operates in symbol units.Alternatively, if a decimator is not provided, the frequency offsetestimator 1092 operates in oversampling units. In the example given inthe description of the present invention, the frequency offset estimator1092 operates in symbol units. Referring to FIG. 33, the frequencyoffset estimator 1092 includes a controller 1310, a first N symbolbuffer 1301, a K symbol delay 1302, a second N symbol buffer 1303, aconjugator 1304, a multiplier 1305, an accumulator 1306, a phasedetector 1307, a multiplier 1308, and a multiplexer 1309. The frequencyoffset estimator 1092 having the above-described structure, as shown inFIG. 33, will now be described in detail with respect to an operationexample during a known data section.

The first N symbol buffer 1301 may store a maximum of N number of symbolbeing inputted thereto. The symbol data that are temporarily stored inthe first N symbol buffer 1301 are then inputted to the multiplier 1305.At the same time, the inputted symbol is inputted to the K symbol delay1302 so as to be delayed by K symbols. Thereafter, the delayed symbolpasses through the second N symbol buffer 1303 so as to be conjugated bythe conjugator 1304. Thereafter, the conjugated symbol is inputted tothe multiplier 1305. The multiplier 1305 multiplies the output of thefirst N symbol buffer 1301 and the output of the conjugator 1304. Then,the multiplier 1305 outputs the multiplied result to the accumulator1306. Subsequently, the accumulator 1306 accumulates the output of themultiplier 1305 during N symbol periods, thereby outputted theaccumulated result to the phase detector 1307.

The phase detector 1307 extracts the corresponding phase informationfrom the output of the accumulator 1306, which is then outputted to themultiplier 1308. The multiplier 1308 then divides the phase informationby K, thereby outputting the divided result to the multiplexer 1309.Herein, the result of the phase information divided by becomes thefrequency offset estimation value. More specifically, at the point wherethe input of the known data ends or at a desired point, the frequencyoffset estimator 1092 accumulates during an N symbol periodmultiplication of the complex conjugate of N number of the input datastored in the first N symbol buffer 1301 and the complex conjugate ofthe N number of the input data that are delayed by K symbols and storedin the second N symbol buffer 1303. Thereafter, the accumulated value isdivided by K, thereby extracting the frequency offset estimation value.

Based upon a control signal of the controller 1310, the multiplexer 1309selects either the output of the multiplier 1308 or ‘0’ and, then,outputs the selected result as the final frequency offset estimationvalue. The controller 1310 receives the known data sequence positionindicator from the known sequence detector and initial frequency offsetestimator 1004-1 in order to control the output of the multiplexer 1309.More specifically, the controller 1310 determines based upon the knowndata sequence position indicator whether the frequency offset estimationvalue being outputted from the multiplier 1308 is valid. If thecontroller 1310 determines that the frequency offset estimation value isvalid, the multiplexer 1309 selects the output of the multiplier 1308.Alternatively, if the controller 1310 determines that the frequencyoffset estimation value is invalid, the controller 1310 generates acontrol signal so that the multiplexer 1309 selects ‘0’. At this point,it is preferable that the input signals stored in the first N symbolbuffer 1301 and in the second N symbol buffer 1303 correspond to signalseach being transmitted by the same known data and passing through almostthe same channel. Otherwise, due to the influence of the transmissionchannel, the frequency offset estimating performance may be largelydeteriorated.

Further, the values N and K of the frequency offset estimator 1092(shown in FIG. 33) may be diversely decided. This is because aparticular portion of the known data that are identically repeated maybe used herein. For example, when the data having the structuredescribed in FIG. 30 are being transmitted, N may be set as BS (i.e.,N=BS), and K may be set as (AS+BS) (i.e., K=AS+BS)). The frequencyoffset estimation value range of the frequency offset estimator 1092 isdecided in accordance with the value K. If the value K is large, thenthe frequency offset estimation value range becomes smaller.Alternatively, if the value K is small, then the frequency offsetestimation value range becomes larger. Therefore, when the data havingthe structure of FIG. 30 is transmitted, and if the repetition cycle(AS+BS) of the known data is long, then the frequency offset estimationvalue range becomes smaller.

In this case, even if the initial frequency offset is estimated by theknown sequence detector and initial frequency offset estimator 1004-1,and if the estimated value is compensated by the second multiplier 1050,the remaining frequency offset after being compensated will exceed theestimation range of the frequency offset estimator 1092. In order toovercome such problems, the known data sequence that is regularlytransmitted may be configured of a repetition of a same data portion byusing a cyclic extension process. For example, if the known datasequence shown in FIG. 30 is configured of two identical portions havingthe length of BS/2, then the N and K values of the frequency offsetestimator 1092 (shown in FIG. 33) may be respectively set as B/2 and B/2(i.e., N=BS/2 and K=BS/2). In this case, the estimation value range maybecome larger than when using repeated known data.

Meanwhile, the known sequence detector and initial frequency offsetestimator 1004-1 detects the place (o position) of the known datasequences that are being periodically or non-periodically transmitted.Simultaneously, the known sequence detector and initial frequency offsetestimator 1004-1 estimates an initial frequency offset during the knownsequence detection process. The known data sequence position indicatordetected by the known sequence detector and initial frequency offsetestimator 1004-1 is outputted to the timing recovery unit 1080, thecarrier recovery unit 1090, and the phase compensator 1110 of thedemodulator 1002, and to the equalizer 1003. Thereafter, the estimatedinitial frequency offset is outputted to the carrier recovery unit 1090.At this point, the known sequence detector and initial frequency offsetestimator 1004-1 may either receive the output of the matched filter1060 or receive the output of the resampler 1040. This may be optionallydecided depending upon the design of the system designer. Herein, thefrequency offset estimator shown in FIG. 33 may be directly applied inthe known sequence detector and initial frequency offset estimator1004-1 or in the phase compensator 1110 of the frequency offsetestimator.

FIG. 34 illustrates a detailed block diagram showing a known sequencedetector and initial frequency offset estimator according to anembodiment of the present invention. More specifically, FIG. 34illustrates an example of an initial frequency offset being estimatedalong with the known sequence position indicator. Herein, FIG. 34 showsan example of an inputted signal being oversampled to N times of itsinitial state. In other words, N represents the sampling rate of areceived signal. Referring to FIG. 34, the known sequence detector andinitial frequency offset estimator includes N number of partialcorrelators 1411 to 141N configured in parallel, a known data placedetector and frequency offset decider 1420, a known data extractor 1430,a buffer 1440, a multiplier 1450, a NCO 1460, a frequency offsetestimator 1470, and an adder 1480. Herein, the first partial correlator1411 consists of a 1/N decimator, and a partial correlator. The secondpartial correlator 1412 consists of a 1 sample delay, a 1/N decimator,and a partial correlator. And, the N^(th) partial correlator 141Nconsists of a N−1 sample delay, a 1/N decimator, and a partialcorrelator. These are used to match (or identify) the phase of each ofthe samples within the oversampled symbol with the phase of the original(or initial) symbol, and to decimate the samples of the remainingphases, thereby performing partial correlation on each sample. Morespecifically, the input signal is decimated at a rate of 1/N for eachsampling phase, so as to pass through each partial correlator.

For example, when the input signal is oversampled to 2 times (i.e., whenN=2), this indicates that two samples are included in one signal. Inthis case, two partial correlators (e.g., 1411 and 1412) are required,and each 1/N decimator becomes a ½ decimator. At this point, the 1/Ndecimator of the first partial correlator 1411 decimates (or removes),among the input samples, the samples located in-between symbol places(or positions). Then, the corresponding 1/N decimator outputs thedecimated sample to the partial correlator. Furthermore, the 1 sampledelay of the second partial correlator 1412 delays the input sample by 1sample (i.e., performs a 1 sample delay on the input sample) and outputsthe delayed input sample to the 1/N decimator. Subsequently, among thesamples inputted from the 1 sample delay, the 1/N decimator of thesecond partial correlator 1412 decimates (or removes) the sampleslocated in-between symbol places (or positions). Thereafter, thecorresponding 1/N decimator outputs the decimated sample to the partialcorrelator.

After each predetermined period of the VSB symbol, each of the partialcorrelators outputs a correlation value and an estimation value of thecoarse frequency offset estimated at that particular moment to the knowndata place detector and frequency offset decider 1420. The known dataplace detector and frequency offset decider 1420 stores the output ofthe partial correlators corresponding to each sampling phase during adata group cycle or a pre-decided cycle. Thereafter, the known dataplace detector and frequency offset decider 1420 decides a position (orplace) corresponding to the highest correlation value, among the storedvalues, as the place (or position) for receiving the known data.Simultaneously, the known data place detector and frequency offsetdecider 1420 finally decides the estimation value of the frequencyoffset estimated at the moment corresponding to the highest correlationvalue as the coarse frequency offset value of the receiving system. Atthis point, the known sequence position indicator is inputted to theknown data extractor 1430, the timing recovery unit 1080, the carrierrecovery unit 1090, the phase compensator 1110, and the equalizer 1003,and the coarse frequency offset is inputted to the adder 1480 and theNCO 1460.

In the meantime, while the N numbers of partial correlators 1411 to 141Ndetect the known data place (or known sequence position) and estimatethe coarse frequency offset, the buffer 1440 temporarily stores thereceived data and outputs the temporarily stored data to the known dataextractor 1430. The known data extractor 1430 uses the known sequenceposition indicator, which is outputted from the known data placedetector and frequency offset decider 1420, so as to extract the knowndata from the output of the buffer 1440. Thereafter, the known dataextractor 1430 outputs the extracted data to the multiplier 1450. TheNCO 1460 generates a complex signal corresponding to the coarsefrequency offset being outputted from the known data place detector andfrequency offset decider 1420. Then, the NCO 1460 outputs the generatedcomplex signal to the multiplier 1450.

The multiplier 1450 multiplies the complex signal of the NCO 1460 to theknown data being outputted from the known data extractor 1430, therebyoutputting the known data having the coarse frequency offset compensatedto the frequency offset estimator 1470. The frequency offset estimator1470 estimates a fine frequency offset from the known data having thecoarse frequency offset compensated. Subsequently, the frequency offsetestimator 1470 outputs the estimated fine frequency offset to the adder1480. The adder 1480 adds the coarse frequency offset to the finefrequency offset. Thereafter, the adder 1480 decides the added result asa final initial frequency offset, which is then outputted to the adder1095 of the carrier recovery unit 1090 included in the demodulator 1002.More specifically, during the process of acquiring initialsynchronization, the present invention may estimate and use the coarsefrequency offset as well as the fine frequency offset, thereby enhancingthe estimation performance of the initial frequency offset.

It is assumed that the known data is inserted within the data group andthen transmitted, as shown in FIG. 10A. Then, the known sequencedetector and initial frequency offset estimator 1004-1 may use the knowndata that have been additionally inserted between the A1 area and the A2area, so as to estimate the initial frequency offset. The known positionindicator, which was periodically inserted within the A area estimatedby the known sequence detector and initial frequency offset estimator1004-1, is inputted to the timing error detector 1083 of the timingerror recovery unit 1080, to the frequency offset estimator 1092 of thecarrier recovery unit 1090, to the frequency offset estimator 1112 ofthe phase compensator 1110, and to the equalizer 1003.

FIG. 35 illustrates a block diagram showing the structure of one of thepartial correlators shown in FIG. 34. During the step of detecting knowndata, since a frequency offset is included in the received signal, eachpartial correlator divides the known data, which is known according toan agreement between the transmitting system and the receiving system,to K number of parts each having an L symbol length, thereby correlatingeach divided part with the corresponding part of the received signal. Inorder to do so, each partial correlator includes K number of phase andsize detector 1511 to 151K each formed in parallel, an adder 1520, and acoarse frequency offset estimator 1530.

The first phase and size detector 1511 includes an L symbol buffer1511-2, a multiplier 1511-3, an accumulator 1511-4, and a squarer1511-5. Herein, the first phase and size detector 1511 calculates thecorrelation value of the known data having a first L symbol length amongthe K number of sections. Also, the second phase and size detector 1512includes an L symbol delay 1512-1, an L symbol buffer 1512-2, amultiplier 1512-3, an accumulator 1512-4, and a squarer 1512-5. Herein,the second phase and size detector 1512 calculates the correlation valueof the known data having a second L symbol length among the K number ofsections. Finally, the N^(th) phase and size detector 151K includes a(K−1)L symbol delay 151K-1, an L symbol buffer 151K-2, a multiplier151K-3, an accumulator 151K-4, and a squarer 151K-5. Herein, the N^(th)phase and size detector 151K calculates the correlation value of theknown data having an N^(th) L symbol length among the K number ofsections.

Referring to FIG. 35, {P₀, P₁, . . . , P_(KL-1)} each being multipliedwith the received signal in the multiplier represents the known dataknown by both the transmitting system and the receiving system (i.e.,the reference known data generated from the receiving system). And, *represents a complex conjugate. For example, in the first phase and sizedetector 1511, the signal outputted from the 1/N decimator of the firstpartial correlator 1411, shown in FIG. 34, is temporarily stored in theL symbol buffer 1511-2 of the first phase and size detector 1511 andthen inputted to the multiplier 1511-3. The multiplier 1511-3 multipliesthe output of the L symbol buffer 1511-2 with the complex conjugate ofthe known data parts P₀, P₁, . . . , P_(KL-1), each having a first Lsymbol length among the known K number of sections. Then, the multipliedresult is outputted to the accumulator 1511-4. During the L symbolperiod, the accumulator 1511-4 accumulates the output of the multiplier1511-3 and, then, outputs the accumulated value to the squarer 1511-5and the coarse frequency offset estimator 1530. The output of theaccumulator 1511-4 is a correlation value having a phase and a size.Accordingly, the squarer 1511-5 calculates an absolute value of theoutput of the multiplier 1511-4 and squares the calculated absolutevalue, thereby obtaining the size of the correlation value. The obtainedsize is then inputted to the adder 1520.

The adder 1520 adds the output of the squares corresponding to each sizeand phase detector 1511 to 151K. Then, the adder 1520 outputs the addedresult to the known data place detector and frequency offset decider1420. Also, the coarse frequency offset estimator 1530 receives theoutput of the accumulator corresponding to each size and phase detector1511 to 151K, so as to estimate the coarse frequency offset at eachcorresponding sampling phase. Thereafter, the coarse frequency offsetestimator 1530 outputs the estimated offset value to the known dataplace detector and frequency offset decider 1420.

When the K number of inputs that are outputted from the accumulator ofeach phase and size detector 1511 to 151K are each referred to as {Z₀,Z₁, . . . , Z_(K-1)}, the output of the coarse frequency offsetestimator 1530 may be obtained by using Equation 7 shown below.

$\begin{matrix}{\omega_{0} = {\frac{1}{L}\mspace{14mu} \arg \mspace{14mu} \left\{ {\sum\limits_{n = 1}^{K - 1}{\left( \frac{Z_{n}}{Z_{n}} \right)\left( \frac{Z_{n - 1}}{Z_{n - 1}} \right)^{*}}} \right\}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

The known data place detector and frequency offset decider 1420 storesthe output of the partial correlator corresponding to each samplingphase during an enhanced data group cycle or a pre-decided cycle. Then,among the stored correlation values, the known data place detector andfrequency offset decider 1420 decides the place (or position)corresponding to the highest correlation value as the place forreceiving the known data.

Furthermore, the known data place detector and frequency offset decider1420 decides the estimated value of the frequency offset taken (orestimated) at the point of the highest correlation value as the coarsefrequency offset value of the receiving system. For example, if theoutput of the partial correlator corresponding to the second partialcorrelator 1412 is the highest value, the place corresponding to thehighest value is decided as the known data place. Thereafter, the coarsefrequency offset estimated by the second partial correlator 1412 isdecided as the final coarse frequency offset, which is then outputted tothe demodulator 1002.

Meanwhile, the output of the second multiplier 1050 is temporarilystored in the decimator 1081 and the buffer 1082 both included in thetiming recovery unit 1080. Subsequently, the temporarily stored outputdata are inputted to the timing error detector 1083 through thedecimator 1081 and the buffer 1082. Assuming that the output of thesecond multiplier 1050 is oversampled to N times its initial state, thedecimator 1081 decimates the output of the second multiplier 1050 at adecimation rate of 1/N. Then, the 1/N-decimated data are inputted to thebuffer 1082. In other words, the decimator 1081 performs decimation onthe input signal in accordance with a VSB symbol cycle. Furthermore, thedecimator 1081 may also receive the output of the matched filter 1060instead of the output of the second multiplier 1050.

The timing error detector 1083 uses the data prior to or after beingprocessed with matched-filtering and the known sequence positionindicator outputted from the known data detector and initial frequencyoffset estimator 1004-1 in order to detect a timing error. Thereafter,the detected timing error is outputted to the loop filter 1084.Accordingly, the detected timing error information is obtained onceduring each repetition cycle of the known data sequence.

For example, if a known data sequence having the same pattern isperiodically inserted and transmitted, as shown in FIG. 30, the timingerror detector 1083 may use the known data in order to detect the timingerror. There exists a plurality of methods for detecting timing error byusing the known data.

In the example of the present invention, the timing error may bedetected by using a correlation characteristic between the known dataand the received data in the time domain, the known data being alreadyknown in accordance with a pre-arranged agreement between thetransmitting system and the receiving system. The timing error may alsobe detected by using the correlation characteristic of the two knowndata types being received in the frequency domain. Thus, the detectedtiming error is outputted. In another example, a spectral lining methodmay be applied in order to detect the timing error. Herein, the spectrallining method corresponds to a method of detecting timing error by usingsidebands of the spectrum included in the received signal.

The loop filter 1084 filters the timing error detected by the timingerror detector 1083 and, then, outputs the filtered timing error to theholder 1085.

The holder 1085 holds (or maintains) the timing error filtered andoutputted from the loop filter 1084 during a pre-determined known datasequence cycle period and outputs the processed timing error to the NCO1086. Herein, the order of positioning of the loop filter 1084 and theholder 1085 may be switched with one another. In additionally, thefunction of the holder 1085 may be included in the loop filter 1084,and, accordingly, the holder 1085 may be omitted.

The NCO 1086 accumulates the timing error outputted from the holder1085. Thereafter, the NCO 1086 outputs the phase element (i.e., asampling clock) of the accumulated timing error to the resampler 1040,thereby adjusting the sampling timing of the resampler 1040.

FIG. 36 illustrates an example of the timing recovery unit included inthe demodulator 1002 shown in FIG. 29. Referring to FIG. 36, the timingrecovery unit 1080 includes a first timing error detector 1611, a secondtiming error detector 1612, a multiplexer 1613, a loop-filter 1614, andan NCO 1615. The timing recovery unit 1080 would be beneficial when theinput signal is divided into a first area in which known data having apredetermined length are inserted at predetermined position(s) and asecond area that includes no known data. Assuming that the first timingerror detector 1611 detects a first timing error using a sideband of aspectrum of an input signal and the second timing error detector 1612detects a second timing error using the known data, the multiplexer 1613can output the first timing error for the first area and can output thesecond timing error for the second area. The multiplexer 1613 may outputboth of the first and second timing errors for the first area in whichthe known data are inserted. By using the known data a more reliabletiming error can be detected and the performance of the timing recoveryunit 1080 can be enhanced.

This disclosure describes two ways of detecting a timing error. One wayis to detect a timing error using correlation in the time domain betweenknown data pre-known to a transmitting system and a receiving system(reference known data) and the known data actually received by thereceiving system, and the other way is to detect a timing error usingcorrelation in the frequency domain between two known data actuallyreceived by the receiving system. In FIG. 37, a timing error is detectedby calculating correlation between the reference known data pre-known toand generated by the receiving system and the known data actuallyreceived. In FIG. 37, correlation between an entire portion of thereference know data sequence and an entire portion of the received knowndata sequence is calculated. The correlation output has a peak value atthe end of each known data sequence actually received.

In FIG. 38, a timing error is detected by calculating correlation valuesbetween divided portions of the reference known data sequence anddivided portions of the received known data sequence, respectively. Thecorrelation output has a peak value at the end of each divided portionof the received known data sequence. The correlation values may be addedas a total correlation value as shown FIG. 38, and the total correlationvalue can be used to calculate the timing error. When an entire portionof the received known data is used for correlation calculation, thetiming error can be obtained for each data block. If the correlationlevel of the entire portion of the known data sequence is low, a moreprecise correlation can be obtained by using divided portions of theknown data sequence as shown in FIG. 38.

The use of a final correlation value which is obtained based upon aplurality of correlation values of divided portions of a received knowndata sequence may reduce the carrier frequency error. In addition, theprocess time for the timing recovery can be greatly reduced when theplurality of correlation values are used to calculate the timing error.For example, when the reference known data sequence which is pre-knownto the transmitting system and receiving system is divided into Kportions, K correlation values between the K portions of the referenceknown data sequence and the corresponding divided portions of thereceived known data sequence can be calculated, or any combination(s) ofthe correlation values can be used. Therefore, the period of the timingerror detection can be reduced when the divided portions of the knowndata sequence are used instead of the entire portion of the sequence.

The timing error can be calculated from the peak value of thecorrelation values. The timing error is obtained for each data block ifan entire portion of the known data sequence is used as shown in FIG.39. On the other hand, if K divided portions of the known data sequenceare used for correlation calculation, K correlation values andcorresponding peak values can be obtained. This indicates that thetiming error can be detected K times.

A method of detecting a timing error using the correlation between thereference known data and the received known data shown will now bedescribed in more detail. FIG. 39 illustrates correlation values betweenthe reference known data and the received known data. The correlationvalues correspond to data samples sampled at a rate two times greaterthan the symbol clock. When the random data effect is minimized andthere is no timing clock error, the correlation values between thereference known data and the received known data are symmetrical.However, if a timing phase error exists, the correlation values adjacentto the peak value are not symmetrical as shown in FIG. 39. Therefore,the timing error can be obtained by using a difference (timing phaseerror shown in FIG. 39) between the correlation values before and afterthe peak value.

FIG. 40 illustrates an example of the timing error detector shown inFIG. 36. The timing error detector includes a correlator 1701, a downsampler 1702, an absolute value calculator 1703, a delay 1704, and asubtractor 1705. The correlator 1701 receives a known data sequencesampled at a rate at least two times higher than the symbol clockfrequency and calculates the correlation values between the receivedknown data sequence and a reference known data sequence. The downsampler 1702 performs down sampling on the correlation values andobtains samples having a symbol frequency. For example, if the datainputted to the correlator 1701 is pre-sampled at a sampling rate of 2,then the down sampler 1702 performs down sampling at a rate of ½ toobtain samples having the symbol frequency. The absolute valuecalculator 1703 calculates absolute values (or square values) of thedown-sampled correlation values. These absolute values are inputted tothe delay 1704 and the subtractor 1705. The delay 1704 delays theabsolute values for a symbol and the subtractor then outputs a timingerror by subtracting the delayed absolute value from the valuesoutputted from the absolute value calculator 1703.

The arrangement of the correlator 1701, the down sampler 1702, theabsolute value calculator 1703, and the delay 1704, and the subtractor1705 shown in FIG. 40 can be modified. For example, the timing phaseerror can be calculated in the order of the down sampler 1702, thecorrelator 1701, and the absolute value calculator 1703, or in the orderof the correlator 1701, the absolute value calculator 1703, and the downsampler 1702.

The timing error can also be obtained using the frequency characteristicof the known data. When there is a timing frequency error, a phase ofthe input signal increases at a fixed slope as the frequency of thesignal increases and this slope is different for current and next datablock. Therefore, the timing error can be calculated based on thefrequency characteristic of two different known data blocks. In FIG. 41,a current known data sequence (right) and a previous known data sequence(left) are converted into first and second frequency domain signals,respectively, using a Fast Fourier Transform (FFT) algorithm. Theconjugate value of the first frequency domain signal is then multipliedwith the second frequency domain signal in order to obtain thecorrelation value between two frequency domain signals. In other words,the correlation between the frequency value of the previous known datasequence and the frequency value of the current known data sequence isused to detect a phase change between the known data blocks for eachfrequency. In this way the phase distortion of a channel can beeliminated.

The frequency response of a complex VSB signal does not have a fullsymmetric distribution as shown in FIG. 39. Rather, its distribution isa left or right half of the distribution and the frequency domaincorrelation values also have a half distribution. In order to the phasedifference between the frequency domain correlation values, thefrequency domain having the correlation values can be divided into twosub-areas and a phase of a combined correlation value in each sub-areacan be obtained. Thereafter, the difference between the phases ofsub-areas can be used to calculate a timing frequency error. When aphase of a combined correlation values is used for each frequency, themagnitude of each correlation value is proportional to reliability and aphase component of each correlation value is reflected to the finalphase component in proportion to the magnitude.

FIG. 42 illustrates another example of the timing error detector shownin FIG. 36. The timing error detector shown in FIG. 42 includes a FastFourier Transform (FFT) unit 1801, a first delay 1802, a conjugator1803, a multiplier 1804, an accumulator (adder) 1805, a phase detector1806, a second delay 1807, and a subtractor 1808. The first delay 1802delays for one data block and the second delay 1807 delays for ¼ datablock. One data block includes a frequency response of a sequence of Nknown data symbol sequences. When a known data region is known and thedata symbols are received, the FFT unit 1801 converts complex values ofconsecutive N known data symbol sequences into complex values in thefrequency domain. The first delay 1802 delays the frequency domaincomplex values for a time corresponding to one data block, and theconjugator 1803 generate conjugate values of the delayed complex values.The multiplier 1804 multiplies the current block of known data outputtedfrom the FFT unit 1801 with the previous block of known data outputtedfrom the conjugator 1803. The output of the multiplier 1804 representsfrequency region correlation values within a known data block.

Since the complex VSB data exist only on a half of the frequency domain,the accumulator 1805 divides a data region in the known data block intotwo sub-regions, and accumulates correlation values for each sub-region.The phase detector 1806 detects a phase of the accumulated correlationvalue for each sub-region. The second delay 1807 delays the detectedphase for a time corresponding to a ¼ data block. The subtractor 1808obtains a phase difference between the delayed phase and the phaseoutputted from the accumulator 1806 and outputs the phase difference asa timing frequency error.

In the method of calculating a timing error by using a peak ofcorrelation between the reference known data and the received known datain the time domain, the contribution of the correlation values mayaffect a channel when the channel is a multi path channel. However, thiscan be greatly eliminated if the timing error is obtained using thecorrelation between two received known data. In addition, the timingerror can be detected using an entire portion of the known data sequenceinserted by the transmitting system, or it can be detected using aportion of the known data sequence which is robust to random or noisedata.

Meanwhile, the DC remover 1070 removes pilot tone signal (i.e., DCsignal), which has been inserted by the transmitting system, from thematched-filtered signal. Thereafter, the DC remover 1070 outputs theprocessed signal to the phase compensator 1110.

FIG. 43 illustrates a detailed block diagram of a DC remover accordingto an embodiment of the present invention. Herein, identical signalprocessing processes are performed on each of a real number element (orin-phase (I)) and an imaginary number element (or a quadrature (Q)) ofthe inputted complex signal, thereby estimating and removing the DCvalue of each element. In order to do so, the DC remover shown in FIG.43 includes a first DC estimator and remover 1900 and a second DCestimator and remover 1950. Herein, the first DC estimator and remover1900 includes an R sample buffer 1901, a DC estimator 1902, an M sampleholder 1903, a C sample delay 1904, and a subtractor 1905. Herein, thefirst DC estimator and remover 1900 estimates and removes the DC of thereal number element (i.e., an in-phase DC). Furthermore, the second DCestimator and remover 1950 includes an R sample buffer 1951, a DCestimator 1952, an M sample holder 1953, a C sample delay 1954, and asubtractor 1955. The second DC estimator and remover 1950 estimates andremoves the DC of the imaginary number element (i.e., a quadrature DC).In the present invention, the first DC estimator and remover 1900 andthe second DC estimator and remover 1950 may receive different inputsignals. However, each DC estimator and remover 1900 and 1950 has thesame structure. Therefore, a detailed description of the first DCestimator and remover 1900 will be presented herein, and the second DCestimator and remover 1950 will be omitted for simplicity.

More specifically, the in-phase signal matched-filtered by the matchedfilter 1060 is inputted to the R sample buffer 1901 of the first DCestimator and remover 1900 within the DC remover 1070 and is thenstored. The R sample buffer 1901 is a buffer having the length of Rsample. Herein, the output of the R sample buffer 1901 is inputted tothe DC estimator 1902 and the C sample delay 1904. The DC estimator 1902uses the data having the length of R sample, which are outputted fromthe buffer 1901, so as to estimate the DC value by using Equation 8shown below.

$\begin{matrix}{{y\lbrack n\rbrack} = {\frac{1}{R}{\sum\limits_{k = 0}^{R - 1}{x\left\lbrack {k + {M*n}} \right\rbrack}}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

In the above-described Equation 8, x[n] represents the inputted sampledata stored in the buffer 1901. And, y[n] indicates the DC estimationvalue. More specifically, the DC estimator 1902 accumulates R number ofsample data stored in the buffer 1901 and estimates the DC value bydividing the accumulated value by R. At this point, the stored inputsample data set is shifted as much as M sample. Herein, the DCestimation value is outputted once every M samples.

FIG. 44 illustrates a shifting of the input sample data used for DCestimation. For example, when M is equal to 1 (i.e., M=1), the DCestimator 1902 estimates the DC value each time a sample is shifted tothe buffer 1901. Accordingly, each estimated result is outputted foreach sample. If M is equal to R (i.e., M=R), the DC estimator 1902estimates the DC value each time R number of samples are shifted to thebuffer 1901. Accordingly, each estimated result is outputted for eachcycle of R samples. Therefore, in this case, the DC estimator 1902corresponds to a DC estimator that operates in a block unit of Rsamples. Herein, any value within the range of 1 and R may correspond tothe value M.

As described above, since the output of the DC estimator 1902 isoutputted after each cycle of M samples, the M sample holder 1903 holdsthe DC value estimated from the DC estimator 1902 for a period of Msamples. Then, the estimated DC value is outputted to the subtractor1905. Also, the C sample delay 1904 delays the input sample data storedin the buffer 1901 by C samples, which are then outputted to thesubtractor 1905. The subtractor 1905 subtracts the output of the Msample holder 1903 from the output of the C sample delay 1904.Thereafter, the subtractor 1905 outputs the signal having the in-phaseDC removed.

Herein, the C sample delay 1904 decides which portion of the inputsample data is to be compensated with the output of the DC estimator1902. More specifically, the DC estimator and remover 1900 may bedivided into a DC estimator 1902 for estimating the DC and thesubtractor for compensating the input sample data within the estimatedDC value. At this point, the C sample delay 1904 decides which portionof the input sample data is to be compensated with the estimated DCvalue. For example, when C is equal to 0 (i.e., C=0), the beginning ofthe R samples is compensated with the estimated DC value obtained byusing R samples. Alternatively, when C is equal to R (i.e., C=R), theend of the R samples is compensated with the estimated DC value obtainedby using R samples. Similarly, the data having the DC removed areinputted to the buffer 1111 and the frequency offset estimator 1112 ofthe phase compensator 1110.

Meanwhile, FIG. 45 illustrates a detailed block diagram of a DC removeraccording to another embodiment of the present invention. Herein,identical signal processing processes are performed on each of a realnumber element (or in-phase (I)) and an imaginary number element (or aquadrature (Q)) of the inputted complex signal, thereby estimating andremoving the DC value of each element. In order to do so, the DC removershown in FIG. 45 includes a first DC estimator and remover 2100 and asecond DC estimator and remover 2150. FIG. 45 corresponds to an infiniteimpulse response (IIR) structure.

Herein, the first DC estimator and remover 2100 includes a multiplier2101, an adder 2102, an 1 sample delay 2103, a multiplier 2104, a Csample delay 2105, and a subtractor 2106. Also, the second DC estimatorand remover 2150 includes a multiplier 2151, an adder 2152, an 1 sampledelay 2153, a multiplier 2154, a C sample delay 2155, and a subtractor2156. In the present invention, the first DC estimator and remover 2100and the second DC estimator and remover 2150 may receive different inputsignals. However, each DC estimator and remover 2100 and 2150 has thesame structure. Therefore, a detailed description of the first DCestimator and remover 2100 will be presented herein, and the second DCestimator and remover 2150 will be omitted for simplicity.

More specifically, the in-phase signal matched-filtered by the matchedfilter 1060 is inputted to the multiplier 2101 and the C sample delay2105 of the first DC estimator and remover 2100 within the DC remover1070. The multiplier 2101 multiplies a pre-determined constant α to thein-phase signal that is being inputted. Then, the multiplier 2101outputs the multiplied result to the adder 2102. The adder 2102 adds theoutput of the multiplier 2101 to the output of the multiplier 2104 thatis being fed-back. Thereafter, the adder 2102 outputs the added resultto the 1 sample delay 2103 and the subtractor 2106. More specifically,the output of the adder 2102 corresponds to the estimated in-phase DCvalue.

The 1 sample delay 2103 delays the estimated DC value by 1 sample andoutputs the DC value delayed by 1 sample to the multiplier 2104. Themultiplier 2104 multiplies a pre-determined constant (1−α) to the DCvalue delayed by 1 sample. Then, the multiplier 2104 feeds-back themultiplied result to the adder 2102.

Subsequently, the C sample delay 2105 delays the in-phase sample data byC samples and, then, outputs the delayed in-phase sample data to thesubtractor 2106. The subtractor 2106 subtracts the output of the adder2102 from the output of the C sample delay 2105, thereby outputting thesignal having the in-phase DC removed therefrom.

Similarly, the data having the DC removed are inputted to the buffer1111 and the frequency offset estimator 1112 of the phase compensator1110 of FIG. 32.

The frequency offset estimator 1112 uses the known sequence positionindicator outputted from the known sequence detector and initialfrequency offset estimator 1004-1 in order to estimate the frequencyoffset from the known data sequence that is being inputted, the knowndata sequence having the DC removed by the DC remover 1070. Then, thefrequency offset estimator 1112 outputs the estimated frequency offsetto the holder 1113. Similarly, the frequency offset estimation value isobtained at each repetition cycle of the known data sequence.

Therefore, the holder 1113 holds the frequency offset estimation valueduring a cycle period of the known data sequence and then outputs thefrequency offset estimation value to the NCO 1114. The NCO 1114generates a complex signal corresponding to the frequency offset held bythe holder 1113 and outputs the generated complex signal to themultiplier 1115.

The multiplier 1115 multiplies the complex signal outputted from the NCO1114 to the data being delayed by a set period of time in the buffer1111, thereby compensating the phase change included in the delayeddata. The data having the phase change compensated by the multiplier1115 pass through the decimator 1200 so as to be inputted to theequalizer 1003. At this point, since the frequency offset estimated bythe frequency offset estimator 1112 of the phase compensator 1110 doesnot pass through the loop filter, the estimated frequency offsetindicates the phase difference between the known data sequences. Inother words, the estimated frequency offset indicates a phase offset.

Channel Equalizer

The demodulated data using the known data in the demodulator 1002 isinputted to the channel equalizer 1003. The demodulated data is inputtedto the known sequence detector 1004.

The equalizer 1003 may perform channel equalization by using a pluralityof methods. An example of estimating a channel impulse response (CIR) soas to perform channel equalization will be given in the description ofthe present invention. Most particularly, an example of estimating theCIR in accordance with each region within the data group, which ishierarchically divided and transmitted from the transmitting system, andapplying each CIR differently will also be described herein.Furthermore, by using the known data, the place and contents of which isknown in accordance with an agreement between the transmitting systemand the receiving system, and/or the field synchronization data, so asto estimate the CIR, the present invention may be able to performchannel equalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to D, as shown in FIG. 10A. More specifically, inthe example of the present invention, each region A, B, C, and D arefurther divided into MPH blocks B4 to B7, MPH blocks B3 and B8, MPHblocks B2 and B9, MPH blocks B1 and B10, respectively.

More specifically, a data group can be assigned and transmitted amaximum the number of 4 in a VSB frame in the transmitting system. Inthis case, all data group do not include field synchronization data. Inthe present invention, the data group including the fieldsynchronization data performs channel-equalization using the fieldsynchronization data and known data. And the data group not includingthe field synchronization data performs channel-equalization using theknown data. For example, the data of the MPH block B3 including thefield synchronization data performs channel-equalization using the CIRcalculated from the field synchronization data area and the CIRcalculated from the first known data area. Also, the data of the MPHblocks B1 and B2 performs channel-equalization using the CIR calculatedfrom the field synchronization data area and the CIR calculated from thefirst known data area. Meanwhile, the data of the MPH blocks B4 to B6not including the field synchronization data performschannel-equalization using CIRS calculated from the first known dataarea and the third known data area.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

FIG. 46 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. Herein, by estimating andcompensating a remaining carrier phase error from a channel-equalizedsignal, the receiving system of the present invention may be enhanced.Referring to FIG. 46, the channel equalizer includes a first frequencydomain converter 3100, a channel estimator 3110, a second frequencydomain converter 3121, a coefficient calculator 3122, a distortioncompensator 3130, a time domain converter 3140, a remaining carrierphase error remover 3150, a noise canceller (NC) 3160, and a decisionunit 3170.

Herein, the first frequency domain converter 3100 includes an overlapunit 3101 overlapping inputted data, and a fast fourier transform (FFT)unit 3102 converting the data outputted from the overlap unit 3101 tofrequency domain data.

The channel estimator 3110 includes a CIR estimator, a phase compensator3112, a pre-CIR cleaner 3113, CIR interpolator/extrapolator 3114, apost-CIR cleaner, and a zero-padding unit.

The second frequency domain converter 3121 includes a fast fouriertransform (FFT) unit converting the CIR being outputted from the channelestimator 3110 to frequency domain CIR.

The time domain converter 3140 includes an IFFT unit 3141 converting thedata having the distortion compensated by the distortion compensator3130 to time domain data, and a save unit 3142 extracting only validdata from the data outputted from the IFFT unit 3141.

The remaining carrier phase error remover 3150 includes an errorcompensator 3151 removing the remaining carrier phase error included inthe channel equalized data, and a remaining carrier phase errorestimator 3152 using the channel equalized data and the decision data ofthe decision unit 3170 so as to estimate the remaining carrier phaseerror, thereby outputting the estimated error to the error compensator3151. Herein, any device performing complex number multiplication may beused as the distortion compensator 3130 and the error compensator 3151.

At this point, since the received data correspond to data modulated toVSB type data, 8-level scattered data exist only in the real numberelement. Therefore, referring to FIG. 46, all of the signals used in thenoise canceller 3160 and the decision unit 3170 correspond to realnumber (or in-phase) signals. However, in order to estimate andcompensate the remaining carrier phase error and the phase noise, bothreal number (in-phase) element and imaginary number (quadrature) elementare required. Therefore, the remaining carrier phase error remover 3150receives and uses the quadrature element as well as the in-phaseelement. Generally, prior to performing the channel equalizationprocess, the demodulator 902 within the receiving system performsfrequency and phase recovery of the carrier. However, if a remainingcarrier phase error that is not sufficiently compensated is inputted tothe channel equalizer, the performance of the channel equalizer may bedeteriorated. Particularly, in a dynamic channel environment, theremaining carrier phase error may be larger than in a static channelenvironment due to the frequent and sudden channel changes. Eventually,this acts as an important factor that deteriorates the receivingperformance of the present invention.

Furthermore, a local oscillator (not shown) included in the receivingsystem should preferably include a single frequency element. However,the local oscillator actually includes the desired frequency elements aswell as other frequency elements. Such unwanted (or undesired) frequencyelements are referred to as phase noise of the local oscillator. Suchphase noise also deteriorates the receiving performance of the presentinvention. It is difficult to compensate such remaining carrier phaseerror and phase noise from the general channel equalizer. Therefore, thepresent invention may enhance the channel equaling performance byincluding a carrier recovery loop (i.e., a remaining carrier phase errorremover 3150) in the channel equalizer, as shown in FIG. 46, in order toremove the remaining carrier phase error and the phase noise.

More specifically, the receiving data demodulated in FIG. 46 areoverlapped by the overlap unit 3101 of the first frequency domainconverter 3100 at a pre-determined overlapping ratio, which are thenoutputted to the FFT unit 3102. The FFT unit 3102 converts theoverlapped time domain data to overlapped frequency domain data throughby processing the data with FFT. Then, the converted data are outputtedto the distortion compensator 3130.

The distortion compensator 3130 performs a complex number multiplicationon the overlapped frequency domain data outputted from the FFT unit 3102included in the first frequency domain converter 3100 and theequalization coefficient calculated from the coefficient calculator3122, thereby compensating the channel distortion of the overlapped dataoutputted from the FFT unit 3102. Thereafter, the compensated data areoutputted to the IFFT unit 3141 of the time domain converter 3140. TheIFFT unit 3141 performs IFFT on the overlapped data having the channeldistortion compensated, thereby converting the overlapped data to timedomain data, which are then outputted to the error compensator 3151 ofthe remaining carrier phase error remover 3150.

The error compensator 3151 multiplies a signal compensating theestimated remaining carrier phase error and phase noise with the validdata extracted from the time domain. Thus, the error compensator 3151removes the remaining carrier phase error and phase noise included inthe valid data.

The data having the remaining carrier phase error compensated by theerror compensator 3151 are outputted to the remaining carrier phaseerror estimator 3152 in order to estimate the remaining carrier phaseerror and phase noise and, at the same time, outputted to the noisecanceller 3160 in order to remove (or cancel) the noise.

The remaining carrier phase error estimator 3152 uses the output data ofthe error compensator 3151 and the decision data of the decision unit3170 to estimate the remaining carrier phase error and phase noise.Thereafter, the remaining carrier phase error estimator 3152 outputs asignal for compensating the estimated remaining carrier phase error andphase noise to the error compensator 3151. In this embodiment of thepresent invention, an inverse number of the estimated remaining carrierphase error and phase noise is outputted as the signal for compensatingthe remaining carrier phase error and phase noise.

FIG. 47 illustrates a detailed block diagram of the remaining carrierphase error estimator 3152 according to an embodiment of the presentinvention. Herein, the remaining carrier phase error estimator 3152includes a phase error detector 3211, a loop filter 3212, a numericallycontrolled oscillator (NCO) 3213, and a conjugator 3214. Referring toFIG. 47, the decision data, the output of the phase error detector 3211,and the output of the loop filter 3212 are all real number signals. And,the output of the error compensator 3151, the output of the NCO 3213,and the output of the conjugator 3214 are all complex number signals.

The phase error detector 3211 receives the output data of the errorcompensator 3151 and the decision data of the decision unit 3170 inorder to estimate the remaining carrier phase error and phase noise.Then, the phase error detector 3211 outputs the estimated remainingcarrier phase error and phase noise to the loop filter.

The loop filter 3212 then filters the remaining carrier phase error andphase noise, thereby outputting the filtered result to the NCO 3213. TheNCO 3213 generates a cosine corresponding to the filtered remainingcarrier phase error and phase noise, which is then outputted to theconjugator 3214.

The conjugator 3214 calculates the conjugate value of the cosine wavegenerated by the NCO 3213. Thereafter, the calculated conjugate value isoutputted to the error compensator 3151. At this point, the output dataof the conjugator 3214 becomes the inverse number of the signalcompensating the remaining carrier phase error and phase noise. In otherwords, the output data of the conjugator 3214 becomes the inverse numberof the remaining carrier phase error and phase noise.

The error compensator 3151 performs complex number multiplication on theequalized data outputted from the time domain converter 3140 and thesignal outputted from the conjugator 3214 and compensating the remainingcarrier phase error and phase noise, thereby removing the remainingcarrier phase error and phase noise included in the equalized data.Meanwhile, the phase error detector 3211 may estimate the remainingcarrier phase error and phase noise by using diverse methods andstructures. According to this embodiment of the present invention, theremaining carrier phase error and phase noise are estimated by using adecision-directed method.

If the remaining carrier phase error and phase noise are not included inthe channel-equalized data, the decision-directed phase error detectoraccording to the present invention uses the fact that only real numbervalues exist in the correlation values between the channel-equalizeddata and the decision data. More specifically, if the remaining carrierphase error and phase noise are not included, and when the input data ofthe phase error detector 3211 are referred to as x_(i)+jx_(q), thecorrelation value between the input data of the phase error detector3211 and the decision data may be obtained by using Equation 9 shownbelow:

E{(x _(i) +jx _(q))({circumflex over (x)} _(i) +j{circumflex over (x)}_(q))^(n)}  Equation 9

At this point, there is no correlation between x_(i) and x_(q).Therefore, the correlation value between x_(i) and x_(q) is equal to 0.Accordingly, if the remaining carrier phase error and phase noise arenot included, only the real number values exist herein. However, if theremaining carrier phase error and phase noise are included, the realnumber element is shown in the imaginary number value, and the imaginarynumber element is shown in the real number value. Thus, in this case,the imaginary number element is shown in the correlation value.Therefore, it can be assumed that the imaginary number portion of thecorrelation value is in proportion with the remaining carrier phaseerror and phase noise. Accordingly, as shown in Equation 10 below, theimaginary number of the correlation value may be used as the remainingcarrier phase error and phase noise.

Phase Error=imag{(x _(i) +jx _(q))({circumflex over (x)} _(i)+j{circumflex over (x)} _(q))^(n)}

Phase Error=x _(q) {circumflex over (x)} _(i) −x _(i) {circumflex over(x)} _(q)  Equation 10

FIG. 48 illustrates a block diagram of a phase error detector 3211obtaining the remaining carrier phase error and phase noise. Herein, thephase error detector 3211 includes a Hilbert converter 3311, a complexnumber configurator 3312, a conjugator 3313, a multiplier 3314, and aphase error output 3315. More specifically, the Hilbert converter 3311creates an imaginary number decision data {circumflex over (x)}_(q) byperforming a Hilbert conversion on the decision value {circumflex over(x)}_(i) of the decision unit 3170. The generated imaginary numberdecision value is then outputted to the complex number configurator3312. The complex number configurator 3312 uses the decision data{circumflex over (x)}_(i) and {circumflex over (x)}_(q) to configure thecomplex number decision data {circumflex over (x)}_(i)+j{circumflex over(x)}_(q), which are then outputted to the conjugator 3313. Theconjugator 3313 conjugates the output of the complex number configurator3312, thereby outputting the conjugated value to the multiplier 3314.The multiplier 3314 performs a complex number multiplication on theoutput data of the error compensator 3151 and the output data{circumflex over (x)}_(i)−j{circumflex over (x)}_(q) of the conjugator3313, thereby obtaining the correlation between the output datax_(i)+jx_(q) of the error compensator 3151 and the decision value{circumflex over (x)}_(i)−j{circumflex over (x)}_(q) of the decisionunit 3170. The correlation data obtained from the multiplier 3314 arethen inputted to the phase error output 3315. The phase error output3315 outputs the imaginary number portion x_(q){circumflex over(x)}_(i)−x_(i){circumflex over (x)}_(q) of the correlation dataoutputted from the multiplier 3314 as the remaining carrier phase errorand phase noise.

The phase error detector shown in FIG. 48 is an example of a pluralityof phase error detecting methods. Therefore, other types of phase errordetectors may be used in the present invention. Therefore, the presentinvention is not limited only to the examples and embodiments presentedin the description of the present invention. Furthermore, according toanother embodiment of the present invention, at least 2 phase errordetectors are combined so as to detect the remaining carrier phase errorand phase noise.

Accordingly, the output of the remaining carrier phase error remover3150 having the detected remaining carrier phase error and phase noiseremoved as described above, is configured of an addition of the original(or initial) signal having the channel equalization, the remainingcarrier phase error and phase noise, and the signal corresponding to awhite noise being amplified to a colored noise during the channelequalization.

Therefore, the noise canceller 3160 receives the output data of theremaining carrier phase error remover 3150 and the decision data of thedecision unit 3170, thereby estimating the colored noise. Then, thenoise canceller 3160 subtracts the estimated colored noise from the datahaving the remaining carrier phase error and phase noise removedtherefrom, thereby removing the noise amplified during the equalizationprocess.

In order to do so, the noise canceller 3160 includes a subtractor and anoise predictor. More specifically, the subtractor subtracts the noisepredicted by the noise predictor from the output data of the residualcarrier phase error estimator 3150. Then, the subtractor outputs thesignal from which amplified noise is cancelled (or removed) for datarecovery and, simultaneously, outputs the same signal to the decisionunit 3170. The noise predictor calculates a noise element by subtractingthe output of the decision unit 3170 from the signal having residualcarrier phase error removed therefrom by the residual carrier phaseerror estimator 3150. Thereafter, the noise predictor uses thecalculated noise element as input data of a filter included in the noisepredictor. Also, the noise predictor uses the filter (not shown) inorder to predict any color noise element included in the output symbolof the residual carrier phase error estimator 3150. Accordingly, thenoise predictor outputs the predicted color noise element to thesubtractor.

The data having the noise removed (or cancelled) by the noise canceller3160 are outputted for the data decoding process and, at the same time,outputted to the decision unit 3170.

The decision unit 3170 selects one of a plurality of pre-determineddecision data sets (e.g., 8 decision data sets) that is most approximateto the output data of the noise canceller 3160, thereby outputting theselected data to the remaining carrier phase error estimator 3152 andthe noise canceller 3160.

Meanwhile, the received data are inputted to the overlap unit 3101 ofthe first frequency domain converter 3100 included in the channelequalizer and, at the same time, inputted to the CIR estimator 3111 ofthe channel estimator 3110.

The CIR estimator 3111 uses a training sequence, for example, data beinginputted during the known data section and the known data in order toestimate the CIR, thereby outputting the estimated CIR to the phasecompensator 3112. If the data to be channel-equalizing is the datawithin the data group including field synchronization data, the trainingsequence using in the CIR estimator 3111 may become the fieldsynchronization data and known data. Meanwhile, if the data to bechannel-equalizing is the data within the data group not including fieldsynchronization data, the training sequence using in the CIR estimator3111 may become only the known data.

For example, the CIR estimator 3111 estimates CIR using the known datacorrespond to reference known data generated during the known datasection by the receiving system in accordance with an agreement betweenthe receiving system and the transmitting system. For this, the CIRestimator 3111 is provided known data position information from theknown sequence detector 1004. Also the CIR estimator 3111 may beprovided field synchronization position information from the knownsequence detector 1004.

Furthermore, in this embodiment of the present invention, the CIRestimator 3111 estimates the CIR by using the least square (LS) method.

The LS estimation method calculates a cross correlation value p betweenthe known data that have passed through the channel during the knowndata section and the known data that are already known by the receivingend. Then, a cross correlation matrix R of the known data is calculated.Subsequently, a matrix operation is performed on R⁻¹·p so that the crosscorrelation portion within the cross correlation value p between thereceived data and the initial known data, thereby estimating the CIR ofthe transmission channel.

The phase compensator 3112 compensates the phase change of the estimatedCIR. Then, the phase compensator 3112 outputs the compensated CIR to thelinear interpolator 3113. At this point, the phase compensator 3112 maycompensate the phase change of the estimated CIR by using a maximumlikelihood method.

More specifically, the remaining carrier phase error and phase noisethat are included in the demodulated received data and, therefore, beinginputted change the phase of the CIR estimated by the CIR estimator 3111at a cycle period of one known data sequence. At this point, if thephase change of the inputted CIR, which is to be used for the linearinterpolation process, is not performed in a linear form due to a highrate of the phase change, the channel equalizing performance of thepresent invention may be deteriorated when the channel is compensated bycalculating the equalization coefficient from the CIR, which isestimated by a linear interpolation method.

Therefore, the present invention removes (or cancels) the amount ofphase change of the CIR estimated by the CIR estimator 3111 so that thedistortion compensator 3130 allows the remaining carrier phase error andphase noise to bypass the distortion compensator 3130 without beingcompensated. Accordingly, the remaining carrier phase error and phasenoise are compensated by the remaining carrier phase error remover 3150.

For this, the present invention removes (or cancels) the amount of phasechange of the CIR estimated by the phase compensator 3112 by using amaximum likelihood method.

The basic idea of the maximum likelihood method relates to estimating aphase element mutually (or commonly) existing in all CIR elements, thento multiply the estimated CIR with an inverse number of the mutual (orcommon) phase element, so that the channel equalizer, and mostparticularly, the distortion compensator 3130 does not compensate themutual phase element.

More specifically, when the mutual phase element is referred to as θ,the phase of the newly estimated CIR is rotated by θ as compared to thepreviously estimated CIR. When the CIR of a point t is referred to ash_(i)(t), the maximum likelihood phase compensation method obtains aphase θ_(ML) corresponding to when h_(i)(t) is rotated by θ, the squaredvalue of the difference between the CIR of h_(i)(t) and the CIR ofh_(i)(t+1), i.e., the CIR of a point (t+1), becomes a minimum value.Herein, when i represents a tap of the estimated CIR, and when Nrepresents a number of taps of the CIR being estimated by the CIRestimator 3111, the value of θ_(ML) is equal to or greater than 0 andequal to or less than N−1. This value may be calculated by usingEquation 11 shown below:

$\begin{matrix}{\theta_{ML} = {\begin{matrix}\min \\\theta\end{matrix}{\sum\limits_{i = 0}^{N - 1}{{{{h_{i}(t)}^{j\theta}} - {h_{i}\left( {t + 1} \right)}}}^{2}}}} & {{Equation}\mspace{14mu} 11}\end{matrix}$

Herein, in light of the maximum likelihood method, the mutual phaseelement θ_(ML) is equal to the value of θ, when the right side ofEquation 11 being differentiated with respect to θ is equal to 0. Theabove-described condition is shown in Equation 12 below:

$\begin{matrix}{{\frac{}{\theta}{\sum\limits_{i = 0}^{N - 1}{{{{h_{i}(t)}^{j\theta}} - {h_{i}\left( {t + 1} \right)}}}^{2}}} = {{\frac{}{\theta}{\sum\limits_{i = 0}^{N - 1}{\left( {{{h_{i}(t)}^{j\theta}} - {h_{i}\left( {t + 1} \right)}} \right)\left( {{{h_{i}(t)}^{j\theta}} - {h_{i}\left( {t + 1} \right)}} \right)^{*}}}} = {{\frac{}{\theta}{\sum\limits_{i = 0}^{N - 1}\left\{ {{{h_{i}(t)}}^{2} + {{h_{i + 1}(t)}}^{2} - {{h_{i}(t)}{h_{i}^{*}\left( {t + 1} \right)}^{j\theta}} - {{h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}^{- {j\theta}}}} \right\}}} = {{\sum\limits_{i = 0}^{N - 1}\left\{ {{j\; {h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}^{- {j\theta}}} - {j\; {h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}^{j\theta}}} \right\}} = {{j{\sum\limits_{i = 0}^{N - 1}{2{Im}\left\{ {{h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}^{- {j\theta}}} \right\}}}} = 0}}}}} & {{Equation}\mspace{14mu} 12}\end{matrix}$

The above Equation 12 may be simplified as shown in Equation 13 below:

$\begin{matrix}{{{{Im}\left\{ {^{- {j\theta}}{\sum\limits_{i = 0}^{N - 1}\left\{ {{h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}} \right\}}} \right\}} = 0}{\theta_{ML} = {\arg \left( {\sum\limits_{i = 0}^{N - 1}{{h_{i}^{*}(t)}{h_{i}\left( {t + 1} \right)}}} \right)}}} & {{Equation}\mspace{14mu} 13}\end{matrix}$

More specifically, Equation 13 corresponds to the θ_(ML) value that isto be estimated by the argument of the correlation value betweenh_(i)(t) and h_(i)(t+1).

FIG. 49 illustrates a phase compensator according to an embodiment ofthe present invention, wherein the mutual phase element θ_(ML) iscalculated as described above, and wherein the estimated phase elementis compensated at the estimated CIR. Referring to FIG. 49, the phasecompensator includes a correlation calculator 3410, a phase changeestimator 3420, a compensation signal generator 3430, and a multiplier3440.

The correlation calculator 3410 includes a first N symbol buffer 3411,an N symbol delay 3412, a second N symbol buffer 3413, a conjugator3414, and a multiplier 3415. More specifically, the first N symbolbuffer 3411 included in the correlation calculator 3410 is capable ofstoring the data being inputted from the CIR estimator 3111 in symbolunits to a maximum limit of N number of symbols. The symbol data beingtemporarily stored in the first N symbol buffer 3411 are then inputtedto the multiplier 3415 included in the correlation calculator 3410 andto the multiplier 3440.

At the same time, the symbol data being outputted from the CIR estimator3111 are delayed by N symbols from the N symbol delay 3412. Then, thedelayed symbol data pass through the second N symbol buffer 3413 andinputted to the conjugator 3414, so as to be conjugated and theninputted to the multiplier 3415.

The multiplier 3415 multiplies the output of the first N symbol buffer3411 and the output of the conjugator 3414. Then, the multiplier 3415outputs the multiplied result to an accumulator 3421 included in thephase change estimator 3420.

More specifically, the correlation calculator 3410 calculates acorrelation between a current CIR h_(i)(t+1) having the length of N anda previous CIR h_(i)(t) also having the length of N. then, thecorrelation calculator 3410 outputs the calculated correlation value tothe accumulator 3421 of the phase change estimator 3420.

The accumulator 3421 accumulates the correlation values outputted fromthe multiplier 3415 during an N symbol period. Then, the accumulator3421 outputs the accumulated value to the phase detector 3422. The phasedetector 3422 then calculates a mutual phase element θ_(ML) from theoutput of the accumulator 3421 as shown in the above-described Equation11. Thereafter, the calculated θ_(ML) value is outputted to thecompensation signal generator 3430.

The compensation signal generator 3430 outputs a complex signal e^(−jθ)^(ML) having a phase opposite to that of the detected phase as the phasecompensation signal to the multiplier 3440. The multiplier 3440multiplies the current CIR h_(i)(t+1) being outputted from the first Nsymbol buffer 3411 with the phase compensation signal e^(−jθ) ^(ML) ,thereby removing the amount of phase change of the estimated CIR.

The CIR having its phase change compensated, as described above, passesthrough a first cleaner (or pre-CIR cleaner) 3113 or bypasses the firstcleaner 3113, thereby being inputted to a CIR calculator (or CIRinterpolator-extrapolator) 3114. The CIR interpolator-extrapolator 3114either interpolates or extrapolates an estimated CIR, which is thenoutputted to a second cleaner (or post-CIR cleaner) 3115. Herein, theestimated CIR corresponds to a CIR having its phase change compensated.The first cleaner 3113 may or may not operate depending upon whether theCIR interpolator-extrapolator 3114 interpolates or extrapolates theestimated CIR. For example, if the CIR interpolator-extrapolator 3114interpolates the estimated CIR, the first cleaner 3113 does not operate.Conversely, if the CIR interpolator-extrapolator 3114 extrapolates theestimated CIR, the first cleaner 3113 operates.

More specifically, the CIR estimated from the known data includes achannel element that is to be obtained as well as a jitter elementcaused by noise. Since such jitter element deteriorates the performanceof the equalizer, it preferable that a coefficient calculator 3122removes the jitter element before using the estimated CIR. Therefore,according to the embodiment of the present invention, each of the firstand second cleaners 3113 and 3115 removes a portion of the estimated CIRhaving a power level lower than the predetermined threshold value (i.e.,so that the estimated CIR becomes equal to ‘0’). Herein, this removalprocess will be referred to as a “CIR cleaning” process.

The CIR interpolator-extrapolator 3114 performs CIR interpolation bymultiplying a CIR estimated from the CIR estimator 3112 by a coefficientand by multiplying a CIR having its phase change compensated from thephase compensator (or maximum likelihood phase compensator) 3112 byanother coefficient, thereby adding the multiplied values. At thispoint, some of the noise elements of the CIR may be added to oneanother, thereby being cancelled. Therefore, when the CIRinterpolator-extrapolator 3114 performs CIR interpolation, the original(or initial) CIR having noise elements remaining therein. In otherwords, when the CIR interpolator-extrapolator 3114 performs CIRinterpolation, an estimated CIR having its phase change compensated bythe phase compensator 3112 bypasses the first cleaner 3113 and isinputted to the CIR interpolator-extrapolator 3114. Subsequently, thesecond cleaner 3115 cleans the CIR interpolated by the CIRinterpolator-extrapolator 3114.

Conversely, the CIR interpolator-extrapolator 3114 performs CIRextrapolation by using a difference value between two CIRs, each havingits phase change compensated by the phase compensator 3112, so as toestimate a CIR positioned outside of the two CIRs. Therefore, in thiscase, the noise element is rather amplified. Accordingly, when the CIRinterpolator-extrapolator 3114 performs CIR extrapolation, the CIRcleaned by the first cleaner 3113 is used. More specifically, when theCIR interpolator-extrapolator 3114 performs CIR extrapolation, theextrapolated CIR passes through the second cleaner 3115, thereby beinginputted to the zero-padding unit 3116.

Meanwhile, when a second frequency domain converter (or fast fouriertransform (FFT2)) 3121 converts the CIR, which has been cleaned andoutputted from the second cleaner 3115, to a frequency domain, thelength and of the inputted CIR and the FFT size may not match (or beidentical to one another). In other words, the CIR length may be smallerthan the FFT size. In this case, the zero-padding unit 3116 adds anumber of zeros ‘0’s corresponding to the difference between the FFTsize and the CIR length to the inputted CIR, thereby outputting theprocessed CIR to the second frequency domain converter (FFT2) 3121.Herein, the zero-padded CIR may correspond to one of the interpolatedCIR, extrapolated CIR, and the CIR estimated in the known data section.

The second frequency domain converter 3121 performs FFT on the CIR beingoutputted from the zero padding unit 3116, thereby converting the CIR toa frequency domain CIR. Then, the second frequency domain converter 3121outputs the converted CIR to the coefficient calculator 3122.

The coefficient calculator 3122 uses the frequency domain CIR beingoutputted from the second frequency domain converter 3121 to calculatethe equalization coefficient. Then, the coefficient calculator 3122outputs the calculated coefficient to the distortion compensator 3130.Herein, for example, the coefficient calculator 3122 calculates achannel equalization coefficient of the frequency domain that canprovide minimum mean square error (MMSE) from the CIR of the frequencydomain, which is outputted to the distortion compensator 3130.

The distortion compensator 3130 performs a complex number multiplicationon the overlapped data of the frequency domain being outputted from theFFT unit 3102 of the first frequency domain converter 3100 and theequalization coefficient calculated by the coefficient calculator 3122,thereby compensating the channel distortion of the overlapped data beingoutputted from the FFT unit 3102.

FIG. 50 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 50illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 10A.

More specifically, as shown in FIG. 10A, known data that aresufficiently are being periodically transmitted in regions A/B (i.e.,MPH blocks B3 to B8). Therefore, an indirect equalizing method using theCIR may be used herein. However, in regions C/D (i.e., MPH blocks B1,B2, B9, and B10), the known data are neither able to be transmitted at asufficiently long length nor able to be periodically and equallytransmitted. Therefore, it is inadequate to estimate the CIR by usingthe known data. Accordingly, in regions C/D, a direct equalizing methodin which an error is obtained from the output of the equalizer, so as toupdate the coefficient.

The examples presented in the embodiments of the present invention shownin FIG. 50 include a method of performing indirect channel equalizationby using a cyclic prefix on the data of regions A/B, and a method ofperforming direct channel equalization by using an overlap & save methodon the data of regions C/D.

Accordingly, referring to FIG. 50, the frequency domain channelequalizer includes a frequency domain converter 3510, a distortioncompensator 3520, a time domain converter 3530, a first coefficientcalculating unit 3540, a second coefficient calculating unit 3550, and acoefficient selector 3560.

Herein, the frequency domain converter 3510 includes an overlap unit3511, a select unit 3512, and a first FFT unit 3513.

The time domain converter 3530 includes an IFFT unit 3531, a save unit3532, and a select unit 3533.

The first coefficient calculating unit 3540 includes a CIR estimator3541, an average calculator 3542, and second FFT unit 3543, and acoefficient calculator 3544.

The second coefficient calculating unit 3550 includes a decision unit3551, a select unit 3552, a subtractor 3553, a zero-padding unit 3554, athird FFT unit 3555, a coefficient updater 3556, and a delay unit 3557.

Also, a multiplexer (MUX), which selects data that are currently beinginputted as the input data depending upon whether the data correspond toregions A/B or to regions C/D, may be used as the select unit 3512 ofthe frequency domain converter 3510, the select unit 3533 of the timedomain converter 3530, and the coefficient selector 3560.

In the channel equalizer having the above-described structure, as shownin FIG. 50, if the data being inputted correspond to the data of regionsA/B, the select unit 3512 of the frequency domain converter 3510 selectsthe input data and not the output data of the overlap unit 3511. In thesame case, the select unit 3533 of the time domain converter 3530selects the output data of the IFFT unit 3531 and not the output data ofthe save unit 3532. The coefficient selector 3560 selects theequalization coefficient being outputted from the first coefficientcalculating unit 3540. Conversely, if the data being inputted correspondto the data of regions C/D, the select unit 3512 of the frequency domainconverter 3510 selects the output data of the overlap unit 3511 and notthe input data. In the same case, the select unit 3533 of the timedomain converter 3530 selects the output data of the save unit 3532 andnot the output data of the IFFT unit 3531. The coefficient selector 3560selects the equalization coefficient being outputted from the secondcoefficient calculating unit 3550.

More specifically, the received data are inputted to the overlap unit3511 and select unit 3512 of the frequency domain converter 3510, and tothe first coefficient calculating unit 3540. If the inputted datacorrespond to the data of regions A/B, the select unit 3512 selects thereceived data, which are then outputted to the first FFT unit 3513. Onthe other hand, if the inputted data correspond to the data of regionsC/D, the select unit 3512 selects the data that are overlapped by theoverlap unit 3513 and are, then, outputted to the first FFT unit 3513.The first FFT unit 3513 performs FFT on the time domain data that areoutputted from the select unit 3512, thereby converting the time domaindata to frequency domain data. Then, the converted data are outputted tothe distortion compensator 3520 and the delay unit 3557 of the secondcoefficient calculating unit 3550.

The distortion compensator 3520 performs complex multiplication onfrequency domain data outputted from the first FFT unit 3513 and theequalization coefficient outputted from the coefficient selector 3560,thereby compensating the channel distortion detected in the data thatare being outputted from the first FFT unit 3513.

Thereafter, the distortion-compensated data are outputted to the IFFTunit 3531 of the time domain converter 3530. The IFFT unit 3531 of thetime domain converter 3530 performs IFFT on thechannel-distortion-compensated data, thereby converting the compensateddata to time domain data. The converted data are then outputted to thesave unit 3532 and the select unit 3533. If the inputted data correspondto the data of regions A/B, the select unit 3533 selects the output dataof the IFFT unit 3531. On the other hand, if the inputted datacorrespond to regions C/D, the select unit 3533 selects the valid dataextracted from the save unit 3532. Thereafter, the selected data areoutputted to be decoded and, simultaneously, outputted to the secondcoefficient calculating unit 3550.

The CIR estimator 3541 of the first coefficient calculating unit 3540uses the data being received during the known data section and the knowndata of the known data section, the known data being already known bythe receiving system in accordance with an agreement between thereceiving system and the transmitting system, in order to estimate theCIR. Subsequently, the estimated CIR is outputted to the averagecalculator 3542. The average calculator 3542 calculates an average valueof the CIRs that are being inputted consecutively. Then, the calculatedaverage value is outputted to the second FFT unit 3543. For example,referring to FIG. 30, the average value of the CIR value estimated atpoint T1 and the CIR value estimated at point T2 is used for the channelequalization process of the general data existing between point T1 andpoint T2. Accordingly, the calculated average value is outputted to thesecond FFT unit 3543.

The second FFT unit 3543 performs FFT on the CIR of the time domain thatis being inputted, so as to convert the inputted CIR to a frequencydomain CIR. Thereafter, the converted frequency domain CIR is outputtedto the coefficient calculator 3544. The coefficient calculator 3544calculates a frequency domain equalization coefficient that satisfiesthe condition of using the CIR of the frequency domain so as to minimizethe mean square error. The calculated equalizer coefficient of thefrequency domain is then outputted to the coefficient calculator 3560.

The decision unit 3551 of the second coefficient calculating unit 3550selects one of a plurality of decision values (e.g., 8 decision values)that is most approximate to the equalized data and outputs the selecteddecision value to the select unit 3552. Herein, a multiplexer may beused as the select unit 3552. In a general data section, the select unit3552 selects the decision value of the decision unit 3551.Alternatively, in a known data section, the select unit 3552 selects theknown data and outputs the selected known data to the subtractor 3553.The subtractor 3553 subtracts the output of the select unit 3533included in the time domain converter 3530 from the output of the selectunit 652 so as to calculate (or obtain) an error value. Thereafter, thecalculated error value is outputted to the zero-padding unit 3554.

The zero-padding unit 3554 adds (or inserts) the same amount of zeros(0) corresponding to the overlapped amount of the received data in theinputted error. Then, the error extended with zeros (0) is outputted tothe third FFT unit 3555. The third FFT unit 3555 converts the error ofthe time domain having zeros (0) added (or inserted) therein, to theerror of the frequency domain. Thereafter, the converted error isoutputted to the coefficient update unit 3556. The coefficient updateunit 3556 uses the received data of the frequency domain that have beendelayed by the delay unit 3557 and the error of the frequency domain soas to update the previous equalization coefficient. Thereafter, theupdated equalization coefficient is outputted to the coefficientselector 3560.

At this point, the updated equalization coefficient is stored so as thatit can be used as a previous equalization coefficient in a laterprocess. If the input data correspond to the data of regions A/B, thecoefficient selector 3560 selects the equalization coefficientcalculated from the first coefficient calculating unit 3540. On theother hand, if the input data correspond to the data of regions C/D, thecoefficient selector 3560 selects the equalization coefficient updatedby the second coefficient calculating unit 3550. Thereafter, theselected equalization coefficient is outputted to the distortioncompensator 3520.

FIG. 51 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 51illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 10A. In this example, a method ofperforming indirect channel equalization by using an overlap & savemethod on the data of regions A/B, and a method of performing directchannel equalization by using an overlap & save method on the data ofregions C/D are illustrated.

Accordingly, referring to FIG. 51, the frequency domain channelequalizer includes a frequency domain converter 3610, a distortioncompensator 3620, a time domain converter 3630, a first coefficientcalculating unit 3640, a second coefficient calculating unit 3650, and acoefficient selector 3660.

Herein, the frequency domain converter 3610 includes an overlap unit3611 and a first FFT unit 3612.

The time domain converter 3630 includes an IFFT unit 3631 and a saveunit 3632.

The first coefficient calculating unit 3640 includes a CIR estimator3641, an interpolator 3642, a second FFT unit 3643, and a coefficientcalculator 3644.

The second coefficient calculating unit 3650 includes a decision unit3651, a select unit 3652, a subtractor 3653, a zero-padding unit 3654, athird FFT unit 3655, a coefficient updater 3656, and a delay unit 3657.

Also, a multiplexer (MUX), which selects data that are currently beinginputted as the input data depending upon whether the data correspond toregions A/B or to regions C/D, may be used as the coefficient selector3660. More specifically, if the input data correspond to the data ofregions A/B, the coefficient selector 3660 selects the equalizationcoefficient calculated from the first coefficient calculating unit 3640.On the other hand, if the input data correspond to the data of regionsC/D, the coefficient selector 3660 selects the equalization coefficientupdated by the second coefficient calculating unit 3650.

In the channel equalizer having the above-described structure, as shownin FIG. 51, the received data are inputted to the overlap unit 3611 ofthe frequency domain converter 3610 and to the first coefficientcalculating unit 3640. The overlap unit 3611 overlaps the input data toa pre-determined overlapping ratio and outputs the overlapped data tothe first FFT unit 3612. The first FFT unit 3612 performs FFT on theoverlapped time domain data, thereby converting the overlapped timedomain data to overlapped frequency domain data. Then, the converteddata are outputted to the distortion compensator 3620 and the delay unit3657 of the second coefficient calculating unit 3650.

The distortion compensator 3620 performs complex multiplication on theoverlapped frequency domain data outputted from the first FFT unit 3612and the equalization coefficient outputted from the coefficient selector3660, thereby compensating the channel distortion detected in theoverlapped data that are being outputted from the first FFT unit 3612.Thereafter, the distortion-compensated data are outputted to the IFFTunit 3631 of the time domain converter 3630. The IFFT unit 3631 of thetime domain converter 3630 performs IFFT on the distortion-compensateddata, thereby converting the compensated data to overlapped time domaindata. The converted overlapped data are then outputted to the save unit3632. The save unit 3632 extracts only the valid data from theoverlapped time domain data, which are then outputted for data decodingand, at the same time, outputted to the second coefficient calculatingunit 3650 in order to update the coefficient.

The CIR estimator 3641 of the first coefficient calculating unit 3640uses the data received during the known data section and the known datain order to estimate the CIR. Subsequently, the estimated CIR isoutputted to the interpolator 3642. The interpolator 3642 uses theinputted CIR to estimate the CIRs (i.e., CIRs of the region that doesnot include the known data) corresponding to the points located betweenthe estimated CIRs according to a predetermined interpolation method.Thereafter, the estimated result is outputted to the second FFT unit3643. The second FFT unit 3643 performs FFT on the inputted CIR, so asto convert the inputted CIR to a frequency domain CIR. Thereafter, theconverted frequency domain CIR is outputted to the coefficientcalculator 3644. The coefficient calculator 3644 calculates a frequencydomain equalization coefficient that satisfies the condition of usingthe CIR of the frequency domain so as to minimize the mean square error.The calculated equalizer coefficient of the frequency domain is thenoutputted to the coefficient calculator 3660.

The structure and operations of the second coefficient calculating unit3650 is identical to those of the second coefficient calculating unit3550 shown in FIG. 50. Therefore, the description of the same will beomitted for simplicity.

If the input data correspond to the data of regions A/B, the coefficientselector 3660 selects the equalization coefficient calculated from thefirst coefficient calculating unit 3640. On the other hand, if the inputdata correspond to the data of regions C/D, the coefficient selector3660 selects the equalization coefficient updated by the secondcoefficient calculating unit 3650. Thereafter, the selected equalizationcoefficient is outputted to the distortion compensator 3620.

FIG. 52 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 52illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 10A. For example, in regions A/B, thepresent invention uses the known data in order to estimate the CIR byusing a least square (LS) method, thereby performing the channelequalization process. On the other hand, in regions C/D, the presentinvention estimates the CIR by using a least mean square (LMS) method,thereby performing the channel equalization process. More specifically,since the periodic known data do not exist in regions C/D, as in regionsA/B, the same channel equalization process as that of regions A/B cannotbe performed in regions C/D. Therefore, the channel equalization processmay only be performed by using the LMS method.

Referring to FIG. 52, the channel equalizer includes an overlap unit3701, a first fast fourier transform (FFT) unit 3702, a distortioncompensator 3703, an inverse fast fourier transform (IFFT) unit 3704, asave unit 3705, a first CIR estimator 3706, a CIR interpolator 3707, adecision unit 3708, a second CIR estimator 3710, a selection unit 3711,a second FFT unit 3712, and a coefficient calculator 3713. Herein, anydevice performed complex number multiplication may be used as thedistortion compensator 3703. In the channel equalizer having theabove-described structure, as shown in FIG. 52, the overlap unit 3701overlaps the data being inputted to the channel equalizer to apredetermined overlapping ratio and then outputs the overlapped data tothe first FFT unit 3702. The first FFT unit 3702 converts (ortransforms) the overlapped data of the time domain to overlapped data ofthe frequency domain by using fast fourier transform (FFT). Then, theconverted data are outputted to the distortion compensator 3703.

The distortion converter 3703 performs complex multiplication on theequalization coefficient calculated from the coefficient calculator 3713and the overlapped data of the frequency domain, thereby compensatingthe channel distortion of the overlapped data being outputted from thefirst FFT unit 3702. Thereafter, the distortion-compensated data areoutputted to the IFFT unit 3704. The IFFT unit 3704 performs inversefast fourier transform (IFFT) on the distortion-compensated overlappeddata, so as to convert the corresponding data back to data (i.e.,overlapped data) of the time domain. Subsequently, the converted dataare outputted to the save unit 3705. The save unit 3705 extracts onlythe valid data from the overlapped data of the time domain. Then, thesave unit 3705 outputs the extracted valid data for a data decodingprocess and, at the same time, outputs the extracted valid data to thedecision unit 3708 for a channel estimation process.

The decision unit 3708 selects one of a plurality of decision values(e.g., 8 decision values) that is most approximate to the equalized dataand outputs the selected decision value to the select unit 3709. Herein,a multiplexer may be used as the select unit 3709. In a general datasection, the select unit 3709 selects the decision value of the decisionunit 3708. Alternatively, in a known data section, the select unit 3709selects the known data and outputs the selected known data to the secondCIR estimator 3710.

Meanwhile, the first CIR estimator 3706 uses the data that are beinginputted in the known data section and the known data so as to estimatethe CIR.

Thereafter, the first CIR estimator 3706 outputs the estimated CIR tothe CIR interpolator 3707. Herein, the known data correspond toreference known data created during the known data section by thereceiving system in accordance to an agreement between the transmittingsystem and the receiving system. At this point, according to anembodiment of the present invention, the first CIR estimator 3706 usesthe LS method to estimate the CIR. The LS estimation method calculates across correlation value p between the known data that have passedthrough the channel during the known data section and the known datathat are already known by the receiving end. Then, a cross correlationmatrix R of the known data is calculated. Subsequently, a matrixoperation is performed on R⁻¹·p so that the cross correlation portionwithin the cross correlation value p between the received data and theinitial known data, thereby estimating the CIR of the transmissionchannel.

The CIR interpolator 3707 receives the CIR from the first CIR estimator3706. And, in the section between two sets of known data, the CIR isinterpolated in accordance with a pre-determined interpolation method.Then, the interpolated CIR is outputted. At this point, thepre-determined interpolation method corresponds to a method ofestimating a particular set of data at an unknown point by using a setof data known by a particular function. For example, such methodincludes a linear interpolation method. The linear interpolation methodis only one of the most simple interpolation methods. A variety of otherinterpolation methods may be used instead of the above-described linearinterpolation method. It is apparent that the present invention is notlimited only to the example set forth in the description of the presentinvention. More specifically, the CIR interpolator 3707 uses the CIRthat is being inputted in order to estimate the CIR of the section thatdoes not include any known data by using the pre-determinedinterpolation method. Thereafter, the estimated CIR is outputted to theselect unit 3711.

The second CIR estimator 3710 uses the input data of the channelequalizer and the output data of the select unit 3709 in order toestimate the CIR. Then, the second CIR estimator 3710 outputs theestimated CIR to the select unit 3711. At this point, according to anembodiment of the present invention, the CIR is estimated by using theLMS method. The LMS estimation method will be described in detail in alater process.

In regions A/B (i.e., MPH blocks B3 to B8), the select unit 3711 selectsthe CIR outputted from the CIR interpolator 3707. And, in regions C/D(i.e., MPH blocks B1, B2, B9, and B10), the select unit 3711 selects theCIR outputted from the second CIR estimator 3710. Thereafter, the selectunit 3711 outputs the selected CIR to the second FFT unit 3712.

The second FFT unit 3712 converts the CIR that is being inputted to aCIR of the frequency domain, which is then outputted to the coefficientcalculator 3713. The coefficient calculator 3713 uses the CIR of thefrequency domain that is being inputted, so as to calculate theequalization coefficient and to output the calculated equalizationcoefficient to the distortion compensator 3703. At this point, thecoefficient calculator 3713 calculates a channel equalizationcoefficient of the frequency domain that can provide minimum mean squareerror (MMSE) from the CIR of the frequency domain. At this point, thesecond CIR estimator 3710 may use the CIR estimated in regions A/B asthe CIR at the beginning of regions C/D. For example, the CIR value ofMPH block B8 may be used as the CIR value at the beginning of the MPHblock B9. Accordingly, the convergence speed of regions C/D may bereduced.

The basic principle of estimating the CIR by using the LMS method in thesecond CIR estimator 3710 corresponds to receiving the output of anunknown transmission channel and to updating (or renewing) thecoefficient of an adaptive filter (not shown) so that the differencevalue between the output value of the unknown channel and the outputvalue of the adaptive filter is minimized. More specifically, thecoefficient value of the adaptive filter is renewed so that the inputdata of the channel equalizer is equal to the output value of theadaptive filter (not shown) included in the second CIR estimator 3710.Thereafter, the filter coefficient is outputted as the CIR after eachFFT cycle.

Referring to FIG. 53, the second CIR estimator 3710 includes a delayunit T, a multiplier, and a coefficient renewal unit for each tab.Herein, the delay unit T sequentially delays the output data x(n) of theselect unit 3709. The multiplier multiplies respective output dataoutputted from each delay unit T with error data e(n). The coefficientrenewal unit renews the coefficient by using the output corresponding toeach multiplier. Herein, the multipliers that are being provided as manyas the number of tabs will be referred to as a first multiplying unitfor simplicity. Furthermore, the second CIR estimator 3710 furtherincludes a plurality of multipliers each multiplying the output data ofthe select unit 3709 and the output data of the delay unit T (whereinthe output data of the last delay unit are excluded) with the outputdata corresponding to each respective coefficient renewal unit. Thesemultipliers are also provided as many as the number of tabs. This groupof multipliers will be referred to as a second multiplying unit forsimplicity.

The second CIR estimator 3710 further includes an adder and asubtractor. Herein, the adder adds all of the data outputted from eachmultipliers included in the second multiplier unit. Then, the addedvalue is outputted as the estimation value ŷ(n) of the data inputted tothe channel equalizer. The subtractor calculates the difference betweenthe output data ŷ(n) of the adder and the input data y(n) of the channelequalizer. Thereafter, the calculated difference value is outputted asthe error data e(n). Referring to FIG. 53, in a general data section,the decision value of the equalized data is inputted to the first delayunit included in the second CIR estimator 3710 and to the firstmultiplier included in the second multiplier. In the known data section,the known data are inputted to the first delay unit included in thesecond CIR estimator 3710 and to the first multiplier included in thesecond multiplier unit. The input data x(n) are sequentially delayed bypassing through a number of serially connected delay units T, the numbercorresponding to the number of tabs. The output data of each delay unitT and the error data e(n) are multiplied by each correspondingmultiplier included in the first multiplier unit. Thereafter, thecoefficients are renewed by each respective coefficient renewal unit.

Each coefficient that is renewed by the corresponding coefficientrenewal unit is multiplied with the input data the output data x(n) andalso with the output data of each delay unit T with the exception of thelast delay. Thereafter, the multiplied value is inputted to the adder.The adder then adds all of the output data outputted from the secondmultiplier unit and outputs the added value to the subtractor as theestimation value ŷ(n) of the input data of the channel equalizer. Thesubtractor calculates a difference value between the estimation valueŷ(n) and the input data y(n) of the channel equalizer. The differencevalue is then outputted to each multiplier of the first multiplier unitas the error data e(n). At this point, the error data e(n) is outputtedto each multiplier of the first multiplier unit by passing through eachrespective delay unit T. As described above, the coefficient of theadaptive filter is continuously renewed. And, the output of eachcoefficient renewal unit is outputted as the CIR of the second CIRestimator 3710 after each FFT cycle.

Block Decoder

Meanwhile, if the data being inputted to the block decoder 1005, afterbeing channel-equalized by the equalizer 1003, correspond to the datahaving both block encoding and trellis encoding performed thereon (i.e.,the data within the RS frame, the signaling information data, etc.) bythe transmitting system, trellis decoding and block decoding processesare performed on the inputted data as inverse processes of thetransmitting system. Alternatively, if the data being inputted to theblock decoder 1005 correspond to the data having only trellis encodingperformed thereon (i.e., the main service data), and not the blockencoding, only the trellis decoding process is performed on the inputteddata as the inverse process of the transmitting system.

The trellis decoded and block decoded data by the block decoder 1005 arethen outputted to the RS frame decoder 1006. More specifically, theblock decoder 1005 removes the known data, data used for trellisinitialization, and signaling information data, MPEG header, which havebeen inserted in the data group, and the RS parity data, which have beenadded by the RS encoder/non-systematic RS encoder or non-systematic RSencoder of the transmitting system. Then, the block decoder 1005 outputsthe processed data to the RS frame decoder 1006. Herein, the removal ofthe data may be performed before the block decoding process, or may beperformed during or after the block decoding process.

Meanwhile, the data trellis-decoded by the block decoder 1005 areoutputted to the data deinterleaver 1009. At this point, the data beingtrellis-decoded by the block decoder 1005 and outputted to the datadeinterleaver 1009 may not only include the main service data but mayalso include the data within the RS frame and the signaling information.Furthermore, the RS parity data that are added by the transmittingsystem after the pre-processor 230 may also be included in the databeing outputted to the data deinterleaver 1009.

According to another embodiment of the present invention, data that arenot processed with block decoding and only processed with trellisencoding by the transmitting system may directly bypass the blockdecoder 1005 so as to be outputted to the data deinterleaver 1009. Inthis case, a trellis decoder should be provided before the datadeinterleaver 1009. More specifically, if the inputted data correspondto the data having only trellis encoding performed thereon and not blockencoding, the block decoder 1005 performs Viterbi (or trellis) decodingon the inputted data so as to output a hard decision value or to performa hard-decision on a soft decision value, thereby outputting the result.

Meanwhile, if the inputted data correspond to the data having both blockencoding process and trellis encoding process performed thereon, theblock decoder 1005 outputs a soft decision value with respect to theinputted data.

In other words, if the inputted data correspond to data being processedwith block encoding by the block processor 302 and being processed withtrellis encoding by the trellis encoding module 256, in the transmittingsystem, the block decoder 1005 performs a decoding process and a trellisdecoding process on the inputted data as inverse processes of thetransmitting system. At this point, the RS frame encoder of thepre-processor included in the transmitting system may be viewed as anouter (or external) encoder. And, the trellis encoder may be viewed asan inner (or internal) encoder. When decoding such concatenated codes,in order to allow the block decoder 1005 to maximize its performance ofdecoding externally encoded data, the decoder of the internal codeshould output a soft decision value.

FIG. 54 illustrates a detailed block diagram of the block decoder 1005according to an embodiment of the present invention. Referring to FIG.54, the block decoder 1005 includes a feedback controller 4010, an inputbuffer 4011, a trellis decoding unit (or 12-way trellis coded modulation(TCM) decoder or inner decoder) 4012, a symbol-byte converter 4013, anouter block extractor 4014, a feedback deformatter 4015, a symboldeinterleaver 4016, an outer symbol mapper 4017, a symbol decoder 4018,an inner symbol mapper 4019, a symbol interleaver 4020, a feedbackformatter 4021, and an output buffer 4022. Herein, just as in thetransmitting system, the trellis decoding unit 4012 may be viewed as aninner (or internal) decoder. And, the symbol decoder 4018 may be viewedas an outer (or external) decoder.

The input buffer 4011 temporarily stores the mobile service data symbolsbeing channel-equalized and outputted from the equalizer 1003. (Herein,the mobile service data symbols may include symbols corresponding to thesignaling information, RS parity data symbols and CRC data symbols addedduring the encoding process of the RS frame.) Thereafter, the inputbuffer 4011 repeatedly outputs the stored symbols for M number of timesto the trellis decoding unit 4012 in a turbo block (TDL) size requiredfor the turbo decoding process.

The turbo decoding length (TDL) may also be referred to as a turboblock. Herein, a TDL should include at least one SCCCC block size.Therefore, as defined in FIG. 10A, when it is assumed that one MPH blockis a 16-segment unit, and that a combination of 10 MPH blocks form oneSCCC block, a TDL should be equal to or larger than the maximum possiblecombination size. For example, when it is assumed that 2 MPH blocks formone SCCC block, the TDL may be equal to or larger than 32 segments(i.e., 828×32=26496 symbols). Herein, M indicates a number ofrepetitions for turbo-decoding pre-decided by the feed-back controller4010.

Also, M represents a number of repetitions of the turbo decodingprocess, the number being predetermined by the feedback controller 4010.

Additionally, among the values of symbols being channel-equalized andoutputted from the equalizer 1003, the input symbol values correspondingto a section having no mobile service data symbols (including RS paritydata symbols during RS frame encoding and CRC data symbols) includedtherein, bypass the input buffer 4011 without being stored. Morespecifically, since trellis-encoding is performed on input symbol valuesof a section wherein SCCC block-encoding has not been performed, theinput buffer 4011 inputs the inputted symbol values of the correspondingsection directly to the trellis encoding module 4012 without performingany storage, repetition, and output processes. The storage, repetition,and output processes of the input buffer 4011 are controlled by thefeedback controller 4010. Herein, the feedback controller 4010 refers toSCCC-associated information (e.g., SCCC block mode and SCCC outer codemode), which are outputted from the signaling information decoding unit1013, in order to control the storage and output processes of the inputbuffer 4011.

The trellis decoding unit 4012 includes a 12-way TCM decoder. Herein,the trellis decoding unit 4012 performs 12-way trellis decoding asinverse processes of the 12-way trellis encoder.

More specifically, the trellis decoding unit 4012 receives a number ofoutput symbols of the input buffer 4011 and soft-decision values of thefeedback formatter 4021 equivalent to each TDL, so as to perform the TCMdecoding process.

At this point, based upon the control of the feedback controller 4010,the soft-decision values outputted from the feedback formatter 4021 arematched with a number of mobile service data symbol places so as to bein a one-to-one (1:1) correspondence. Herein, the number of mobileservice data symbol places is equivalent to the TDL being outputted fromthe input buffer 4011.

More specifically, the mobile service data being outputted from theinput buffer 4011 are matched with the turbo decoded data beinginputted, so that each respective data place can correspond with oneanother. Thereafter, the matched data are outputted to the trellisdecoding unit 4012. For example, if the turbo decoded data correspond tothe third symbol within the turbo block, the corresponding symbol (ordata) is matched with the third symbol included in the turbo block,which is outputted from the input buffer 4011. Subsequently, the matchedsymbol (or data) is outputted to the trellis decoding unit 4012.

In order to do so, while the regressive turbo decoding is in process,the feedback controller 4010 controls the input buffer 4011 so that theinput buffer 4011 stores the corresponding turbo block data. Also, bydelaying data (or symbols), the soft decision value (e.g., LLR) of thesymbol outputted from the symbol interleaver 4020 and the symbol of theinput buffer 4011 corresponding to the same place (or position) withinthe block of the output symbol are matched with one another to be in aone-to-one correspondence. Thereafter, the matched symbols arecontrolled so that they can be inputted to the TCM decoder through therespective path. This process is repeated for a predetermined number ofturbo decoding cycle periods. Then, the data of the next turbo block areoutputted from the input buffer 4011, thereby repeating the turbodecoding process.

The output of the trellis decoding unit 4012 signifies a degree ofreliability of the transmission bits configuring each symbol. Forexample, in the transmitting system, since the input data of the trellisencoding module correspond to two bits as one symbol, a log likelihoodratio (LLR) between the likelihood of a bit having the value of ‘1’ andthe likelihood of the bit having the value of ‘0’ may be respectivelyoutputted (in bit units) to the upper bit and the lower bit. Herein, thelog likelihood ratio corresponds to a log value for the ratio betweenthe likelihood of a bit having the value of ‘1’ and the likelihood ofthe bit having the value of ‘0’. Alternatively, a LLR for the likelihoodof 2 bits (i.e., one symbol) being equal to “00”, “01”, “10”, and “11”may be respectively outputted (in symbol units) to all 4 combinations ofbits (i.e., 00, 01, 10, 11). Consequently, this becomes the softdecision value that indicates the degree of reliability of thetransmission bits configuring each symbol. A maximum a posterioriprobability (MAP) or a soft-out Viterbi algorithm (SOVA) may be used asa decoding algorithm of each TCM decoder within the trellis decodingunit 4012.

The output of the trellis decoding unit 4012 is inputted to thesymbol-byte converter 4013 and the outer block extractor 4014.

The symbol-byte converter 4013 performs a hard-decision process of thesoft decision value that is trellis decoded and outputted from thetrellis decoding unit 4012. Thereafter, the symbol-byte converter 4013groups 4 symbols into byte units, which are then outputted to the datadeinterleaver 1009 of FIG. 29. More specifically, the symbol-byteconverter 4013 performs hard-decision in bit units on the soft decisionvalue of the symbol outputted from the trellis decoding unit 4012.Therefore, the data processed with hard-decision and outputted in bitunits from the symbol-byte converter 4013 not only include main servicedata, but may also include mobile service data, known data, RS paritydata, and MPEG headers.

Among the soft decision values of TDL size of the trellis decoding unit4012, the outer block extractor 4014 identifies the soft decision valuesof B size of corresponding to the mobile service data symbols (whereinsymbols corresponding to signaling information, RS parity data symbolsthat are added during the encoding of the RS frame, and CRC data symbolsare included) and outputs the identified soft decision values to thefeedback deformatter 4015.

The feedback deformatter 4015 changes the processing order of the softdecision values corresponding to the mobile service data symbols. Thisis an inverse process of an initial change in the processing order ofthe mobile service data symbols, which are generated during anintermediate step, wherein the output symbols outputted from the blockprocessor 302 of the transmitting system are being inputted to thetrellis encoding module 256 (e.g., when the symbols pass through thegroup formatter, the data deinterleaver, the packet formatter, and thedata interleaver). Thereafter, the feedback deformatter 1015 performsreordering of the process order of soft decision values corresponding tothe mobile service data symbols and, then, outputs the processed mobileservice data symbols to the symbol deinterleaver 4016.

This is because a plurality of blocks exist between the block processor302 and the trellis encoding module 256, and because, due to theseblocks, the order of the mobile service data symbols being outputtedfrom the block processor 302 and the order of the mobile service datasymbols being inputted to the trellis encoding module 256 are notidentical to one another. Therefore, the feedback deformatter 4015reorders (or rearranges) the order of the mobile service data symbolsbeing outputted from the outer block extractor 4014, so that the orderof the mobile service data symbols being inputted to the symboldeinterleaver 4016 matches the order of the mobile service data symbolsoutputted from the block processor 302 of the transmitting system. Thereordering process may be embodied as one of software, middleware, andhardware.

FIG. 55 illustrates a detailed block view of the feedback deformatter4015 according to an embodiment of the present invention. Herein, thefeedback deformatter 4015 includes a data deinterleaver 5011, a packetdeformatter 5012, a data interleaver 5013, and a group deformatter 5014.Referring to FIG. 55, the soft decision value of the mobile service datasymbol, which is extracted by the outer block extractor 4014, isoutputted directly to the data deinterleaver 5011 of the feedbackdeformatter 4015 without modification. However, data place holders (ornull data) are inserted in data places (e.g., main service data places,known data places, signaling information places, RS parity data places,and MPEG header places), which are removed by the outer block extractor4014, thereby being outputted to the data deinterleaver 5011 of thefeedback deformatter 4015.

The data deinterleaver 5011 performs an inverse process of the datainterleaver 253 included in the transmitting system. More specifically,the data deinterleaver 5011 deinterleaves the inputted data and outputsthe deinterleaved data to the packet deformatter 5012. The packetdeformatter 5012 performs an inverse process of the packet formatter305. More specifically, among the data that are deinterleaved andoutputted from the data deinterleaver 5011, the packet deformatter 5012removes the place holder corresponding to the MPEG header, which hadbeen inserted to the packet formatter 305. The output of the packetdeformatter 5012 is inputted to the data interleaver 5013, and the datainterleaver 5013 interleaves the data being inputted, as an inverseprocess of the data deinterleaver 529 included in the transmittingsystem. Accordingly, data having a data structure as shown in FIG. 10A,are outputted to the group deformatter 5014.

The data deformatter 5014 performs an inverse process of the groupformatter 303 included in the transmitting system. More specifically,the group formatter 5014 removes the place holders corresponding to themain service data, known data, signaling information data, and RS paritydata. Then, the group formatter 5014 outputs only the reordered (orrearranged) mobile service data symbols to the symbol deinterleaver4016. According to another embodiment of the present invention, when thefeedback deformatter 4015 is embodied using a memory map, the process ofinserting and removing place holder to and from data places removed bythe outer block extractor 4014 may be omitted.

The symbol deinterleaver 4016 performs deinterleaving on the mobileservice data symbols having their processing orders changed andoutputted from the feedback deformatter 4015, as an inverse process ofthe symbol interleaving process of the symbol interleaver 514 includedin the transmitting system. The size of the block used by the symboldeinterleaver 4016 during the deinterleaving process is identical tointerleaving size of an actual symbol (i.e., B) of the symbolinterleaver 514, which is included in the transmitting system. This isbecause the turbo decoding process is performed between the trellisdecoding unit 4012 and the symbol decoder 4018. Both the input andoutput of the symbol deinterleaver 4016 correspond to soft decisionvalues, and the deinterleaved soft decision values are outputted to theouter symbol mapper 4017.

The operations of the outer symbol mapper 4017 may vary depending uponthe structure and coding rate of the convolution encoder 513 included inthe transmitting system. For example, when data are ½-rate encoded bythe convolution encoder 513 and then transmitted, the outer symbolmapper 4017 directly outputs the input data without modification. Inanother example, when data are ¼-rate encoded by the convolution encoder513 and then transmitted, the outer symbol mapper 4017 converts theinput data so that it can match the input data format of the symboldecoder 4018. For this, the outer symbol mapper 4017 may be inputtedSCCC-associated information (i.e., SCCC block mode and SCCC outer codemode) from the signaling information decoder 1013. Then, the outersymbol mapper 4017 outputs the converted data to the symbol decoder4018.

The symbol decoder 4018 (i.e., the outer decoder) receives the dataoutputted from the outer symbol mapper 4017 and performs symbol decodingas an inverse process of the convolution encoder 513 included in thetransmitting system. At this point, two different soft decision valuesare outputted from the symbol decoder 4018. One of the outputted softdecision values corresponds to a soft decision value matching the outputsymbol of the convolution encoder 513 (hereinafter referred to as a“first decision value”). The other one of the outputted soft decisionvalues corresponds to a soft decision value matching the input bit ofthe convolution encoder 513 (hereinafter referred to as a “seconddecision value”).

More specifically, the first decision value represents a degree ofreliability the output symbol (i.e., 2 bits) of the convolution encoder513. Herein, the first soft decision value may output (in bit units) aLLR between the likelihood of 1 bit being equal to ‘1’ and thelikelihood of 1 bit being equal to ‘0’ with respect to each of the upperbit and lower bit, which configures a symbol. Alternatively, the firstsoft decision value may also output (in symbol units) a LLR for thelikelihood of 2 bits being equal to “00”, “01”, “10”, and “11” withrespect to all possible combinations. The first soft decision value isfed-back to the trellis decoding unit 4012 through the inner symbolmapper 4019, the symbol interleaver 4020, and the feedback formatter4021. On the other hand, the second soft decision value indicates adegree of reliability the input bit of the convolution encoder 513included in the transmitting system. Herein, the second soft decisionvalue is represented as the LLR between the likelihood of 1 bit beingequal to ‘1’ and the likelihood of 1 bit being equal to ‘0’. Thereafter,the second soft decision value is outputted to the outer buffer 4022. Inthis case, a maximum a posteriori probability (MAP) or a soft-outViterbi algorithm (SOVA) may be used as the decoding algorithm of thesymbol decoder 4018.

The first soft decision value that is outputted from the symbol decoder4018 is inputted to the inner symbol mapper 4019. The inner symbolmapper 4019 converts the first soft decision value to a data formatcorresponding the input data of the trellis decoding unit 4012.Thereafter, the inner symbol mapper 4019 outputs the converted softdecision value to the symbol interleaver 4020. The operations of theinner symbol mapper 4019 may also vary depending upon the structure andcoding rate of the convolution encoder 513 included in the transmittingsystem.

Hereinafter, when the symbol encoder 402 of the transmitting systemoperates as a ¼ encoder, the operations of the outer symbol mapper 4017and the inner symbol mapper 4019 will now be described in detail withreference to FIG. 21A to FIG. 21C.

According to an embodiment of the present invention, it is assumed thatthe symbol encoder is configured as shown in FIG. 21A, and that the ¼outer encoder 411 encodes one bit U so as to output 4 bits u0, u1, u2,and u3, and also that the 4 bits (i.e., 2 symbols) are transmitted twicein symbol units (i.e., each of the 2 symbols is transmitted twice)through the parallel/serial converter 412. In this case, the symbol thatis outputted first is referred to as an odd-number-designated symbol,and the symbol that is outputted subsequently is referred to as aneven-number-designated symbol for simplicity.

At this point, when the input/output units of the outer symbol mapper4017 and the inner symbol mapper 4019 corresponds to symbol units, 16(i.e., 2⁴=16) different soft decision values may be outputted in symbolunits from the outer symbol mapper 4017. For example, among the 16(i.e., 2⁴=16) different soft decision values that are to be outputtedfrom the outer symbol mapper 4017, the soft decision value of s=(1, 0,0, 1) may be calculated by adding the soft decision value of theinputted odd-number-designated symbol m₀=(1, 0) and the soft decisionvalue of the inputted even-number-designated symbol m₁=(0, 1).Afterwards, the added value is inputted to the symbol decoder 4018.

Furthermore, a total of 4 (i.e., 2²=4) different soft decision valuesmay be outputted in symbol units from the inner symbol mapper 4019. Forexample, among the 4 (i.e., 2²=4) different soft decision values thatare to be outputted from the inner symbol mapper 4019, the soft decisionvalue of the odd-number-designated symbol m₀=(1, 1) may be obtained bycalculating the largest value among the soft decision value for each ofthe output symbols s=(1, 1, X, X) outputted from the symbol decoder4018. Afterwards, the added value is inputted to the symbol decoder4018. Also, the soft decision value of the even-number-designated symbolm₁=(0, 0) may be obtained by calculating the largest value among thesoft decision value for each of the output symbols s=(X, X, 0, 0)outputted from the symbol decoder 4018. Herein, ‘X’ randomly correspondsto one of ‘1’ and ‘0’. The output of the inner symbol mapper 4019 isthen provided to the symbol interleaver 4020.

Meanwhile, if the input/output units of the outer symbol mapper 4017 andthe inner symbol mapper 4019 correspond to bit units, a total of 4different soft decision values may be outputted in bit units from theouter symbol mapper 4017.

More specifically, the outer symbol mapper 4017 simultaneously outputs 2soft decision values of an odd-number-designated input symbol (i.e., asoft decision value for each of the upper bit and lower bit configuringthe odd-number-designated input symbol) and 2 soft decision values of aneven-number-designated input symbol (i.e., a soft decision value foreach of the upper bit and lower bit configuring theeven-number-designated input symbol) to the symbol decoder 4018. Also,with respect to the 4 inputs provided by the symbol decoder 4018, theinner symbol mapper 4019 also identifies 2 soft decision values of anodd-number-designated output symbol (i.e., a soft decision value foreach of the upper bit and lower bit configuring theodd-number-designated output symbol of the symbol decoder 4018) and 2soft decision values of an even-number-designated output symbol (i.e., asoft decision value for each of the upper bit and lower bit configuringthe even-number-designated output symbol of the symbol decoder 4018),which are then outputted to the symbol interleaver 4020.

In other words, if the symbol encoding process is performed as shown inFIG. 21A, the LLR for each of the 16 symbols is respectively receivedand symbol-decoded. Thereafter, the processed LLR for each of the 16symbols may be outputted as the first soft decision value.Alternatively, the LLR for each of the 4 symbols is respectivelyreceived and symbol-decoded. Thereafter, the processed LLR for each ofthe 4 symbols may be outputted as the first soft decision value.

According to another embodiment of the present invention, it is assumedthat the symbol encoder is configured as shown in FIG. 21B, and that the½ outer encoder 421 encodes one bit U so as to output 2 bits u0 and u1,and also that the 2 bits (i.e., 1 symbol) is repeated once through therepeater 422. In this case, the symbol that is outputted first isreferred to as an odd-number-designated symbol, and the symbol that isoutputted subsequently is referred to as an even-number-designatedsymbol for simplicity.

At this point, when the input/output units of the outer symbol mapper4017 and the inner symbol mapper 4019 corresponds to symbol units, 4(i.e., 2²=4) different soft decision values may be outputted in symbolunits from the outer symbol mapper 4017. For example, among the 4 (i.e.,2²=4) different soft decision values that are to be outputted in symbolunits from the outer symbol mapper 4017, the soft decision value ofs=(1, 0) may be calculated by adding the soft decision value of theinputted odd-number-designated symbol m₀=(1, 0) and the soft decisionvalue of the inputted even-number-designated symbol m₁=(1, 0).Afterwards, the added value is provided to the symbol decoder 4018.Furthermore, a total of 4 (i.e., 2²=4) different soft decision values isto be outputted from the inner symbol mapper 4019. For example, amongthe 4 (i.e., 2²=4) different soft decision values, the soft decisionvalue of the odd-number-designated symbol m₀=(1, 1) and theeven-number-designated symbol m₁=(1, 1) become the soft decision valueof the input symbol s=(1, 1) of the symbol decoder 4018. This softdecision value is then outputted to the symbol interleaver 4020.

Meanwhile, if the input/output units of the outer symbol mapper 4017 andthe inner symbol mapper 4019 correspond to bit units, a total of 2 softdecision values (i.e., a soft decision for the upper bit and a softdecision value for the lower bit) may be outputted in bit units from theouter symbol mapper 4017. Herein, the soft decision value for the upperbit may be obtained by adding the soft decision for the upper bit of theodd-number-designated symbol and the soft decision for the upper bit ofthe even-number-designated symbol. Also, the soft decision value for thelower bit may be obtained by adding the soft decision for the lower bitof the odd-number-designated symbol and the soft decision for the lowerbit of the even-number-designated symbol.

The inner symbol mapper 4019 receives the soft decision value for theupper bit and the soft decision value for the lower bit from the symboldecoder 4018. Thereafter, the inner symbol mapper 4019 outputs thereceived soft decision values as 2 soft decision values corresponding toeach of the odd-number-designated output bits (i.e., a soft decisionvalue for each of the lower bit and upper bit that are outputted fromthe symbol decoder 4018). Then, the 2 soft decision values correspondingto each of the odd-number-designated output bits are repeated, therebybeing outputted as 2 soft decision values corresponding to each of theeven-number-designated output bits.

According to yet another embodiment of the present invention, it isassumed that the symbol encoder is configured as shown in FIG. 21C, andthat the input bit is repeated once by the repeater 431, and that the ½outer encoder 432 ½-rate encodes the bit that is repeated and inputtedfrom the repeater 431, so as to output 2 bits u0 and u1 (i.e., 1 symbol)twice. In this case, the symbol encoder repeats one bit and encodes therepeated bit at a coding rate of ½. Herein, the symbol that is outputtedfirst is referred to as an odd-number-designated symbol, and the symbolthat is outputted subsequently is referred to as aneven-number-designated symbol for simplicity.

At this point, if the input/output units of the outer symbol mapper 4017and the inner symbol mapper 4019 correspond to bit units, the outersymbol mapper 4017 directly transmits the output of the symboldeinterleaver 4016 to the symbol decoder 4018 without modification. Theinner symbol mapper 4019 directly transmits the output of the symboldecoder 4018 to the symbol interleaver 4020 without modification. Also,even when the input/output units of the outer symbol mapper 4017 and theinner symbol mapper 4019 correspond to symbol units, the outer symbolmapper 4017 directly transmits the output of the symbol deinterleaver4016 to the symbol decoder 4018 without modification. The inner symbolmapper 4019 directly transmits the output of the symbol decoder 4018 tothe symbol interleaver 4020 without modification.

Referring to FIG. 21C, since the input of the ½ outer encoder 432 isrepeated by the repeater 431, the soft decisions values for the 2symbols corresponding to the output data of the block decoder should bedetermined and outputted as a single soft decision value. Morespecifically, when the symbol encoding is processed as shown in FIG. 21Band FIG. 21C, the LLR for each of the 4 different symbols may bereceived and symbol-decoded. Thereafter, the LLR for each of the 4symbols may be outputted as the first soft decision value.Alternatively, the LLR for 2 bits may be received and symbol-decoded.Thereafter, the LLR for the 2 bits may be outputted as the first softdecision value.

The symbol interleaver 4020 performs symbol interleaving, as shown inFIG. 23, on the first soft decision value that is outputted from theinner symbol mapper 4019. Then, the symbol interleaver 4020 outputs thesymbol-interleaved first soft decision value to the feedback formatter4021. Herein, the output of the symbol interleaver 4020 also correspondsto a soft decision value. With respect to the changed processing orderof the soft decision values corresponding to the symbols that aregenerated during an intermediate step, wherein the output symbolsoutputted from the block processor 303 of the transmitting system arebeing inputted to the trellis encoding module (e.g., when the symbolspass through the group formatter, the data deinterleaver, the packetformatter, the RS encoder, and the data interleaver), the feedbackformatter 4021 alters (or changes) the order of the output valuesoutputted from the symbol interleaver 4020. Subsequently, the feedbackformatter 4020 outputs values to the trellis decoding unit 4012 in thechanged order.

The soft decision values outputted from the symbol interleaver 4020 arematched with the positions of mobile service data symbols each havingthe size of TDL, which are outputted from the input buffer 4011, so asto be in a one-to-one correspondence. Thereafter, the soft decisionvalues matched with the respective symbol position are inputted to thetrellis decoding unit 4012. At this point, since the main service datasymbols or the RS parity data symbols and known data symbols of the mainservice data do not correspond to the mobile service data symbols, thefeedback formatter 4021 inserts null data in the correspondingpositions, thereby outputting the processed data to the trellis decodingunit 4012. Additionally, each time the symbols having the size of TDLare turbo decoded, no value is fed-back by the symbol interleaver 4020starting from the beginning of the first decoding process. Therefore,the feedback formatter 4021 is controlled by the feedback controller4010, thereby inserting null data into all symbol positions including amobile service data symbol. Then, the processed data are outputted tothe trellis decoding unit 4012.

The output buffer 4022 receives the second soft decision value from thesymbol decoder 4018 based upon the control of the feedback controller4010. Then, the output buffer 4022 temporarily stores the receivedsecond soft decision value. Thereafter, the output buffer 4022 outputsthe second soft decision value to the RS frame deocder 1006. Forexample, the output buffer 4022 overwrites the second soft decisionvalue of the symbol decoder 4018 until the turbo decoding process isperformed for M number of times. Then, once all M number of turbodecoding processes is performed for a single TDL, the correspondingsecond soft decision value is outputted to the RS frame deocder 1006.

The feedback controller 4010 controls the number of turbo decoding andturbo decoding repetition processes of the overall block decoder, shownin FIG. 54.

At this point, the number of regressive turbo decoding rounds betweenthe trellis decoding unit 4012 and the symbol decoder 4018 may bedefined while taking into account hardware complexity and errorcorrection performance. Accordingly, if the number of rounds increases,the error correction performance may be enhanced. However, this may leadto a disadvantageous of the hardware becoming more complicated (orcomplex).

Meanwhile, the data deinterleaver 1009, the RS decoder 1010, and thedata derandomizer 1011 correspond to blocks required for receiving themain service data. Therefore, the above-mentioned blocks may not benecessary (or required) in the structure of a digital broadcastreceiving system for receiving mobile service data only. The datadeinterleaver 1009 performs an inverse process of the data interleaverincluded in the transmitting system. In other words, the datadeinterleaver 1009 deinterleaves the main service data outputted fromthe block decoder 1005 and outputs the deinterleaved main service datato the RS decoder 4010. The data being inputted to the datadeinterleaver 1009 include main service data, as well as mobile servicedata, known data, RS parity data, and an MPEG header.

The RS decoder 1010 performs a systematic RS decoding process on thedeinterleaved data and outputs the processed data to the dataderandomizer 1011.

The data derandomizer 1011 receives the output of the RS decoder 1010and generates a pseudo random data byte identical to that of therandomizer included in the digital broadcast transmitting system.Thereafter, the data derandomizer 1011 performs a bitwise exclusive OR(XOR) operation on the generated pseudo random data byte, therebyinserting the MPEG synchronization bytes to the beginning of each packetso as to output the data in 188-byte main service data packet units.

RS Frame Decoder

More specifically, the RS frame decoder 1006 receives only theRS-encoded and/or CRC-encoded mobile service data that are transmittedfrom the block decoder 1005. The RS frame encoder 1006 performs aninverse process of the RS frame encoder included in the transmittingsystem so as to correct the error within the RS frame. Then, the RSframe decoder 1006 adds the 1-byte MPEG synchronization service datapacket, which had been removed during the RS frame encoding process, tothe error-corrected mobile service data packet. Thereafter, theprocessed data packet is outputted to the derandomizer 1007.

FIG. 56 illustrates a process of grouping a plurality of data groups(e.g., 18 data groups) to create a RS frame and a RS frame reliabilitymap, and also a process of performing data deinterleaving in super frameunits as an inverse process of the transmitting system and identifyingthe deinterleaved RS frame and RS frame reliability map. Morespecifically, the RS frame decoder 1006 groups the inputted mobileservice data so as to create a RS frame. The mobile service data havebeen RS-encoded RS frame units by the transmitting system, and theninterleaved in super frame units. At this point, the error correctionencoding process (e.g., the CRC encoding process) may have beenperformed on the mobile service data, or the error correction encodingprocess may have been omitted.

If it is assumed that the transmitting system has divided the RS framehaving the size of (N+2)*(187+P) bytes into M number of data groups(wherein, for example, M is equal to 18) and then transmitted thedivided RS frame, the receiving system groups the mobile service data ofeach data group, as shown in FIG. 56( a), so as to create a RS framehaving the size of (N+2)*(187+P) bytes. At this point, if a dummy bytehas been added to at least one of the data groups configuring thecorresponding RS frame and, then, transmitted, the dummy byte isremoved, and a RS frame and a RS frame reliability map are created. Forexample, as shown in FIG. 11, if K number of dummy bytes has been added,the RS frame and RS frame reliability map are created after the K numberof dummy bytes has been removed.

Furthermore, if it is assumed that the RS frame is divided into 18 datagroups, which are then transmitted from a single burst-on section, thereceiving system also groups mobile service data of 18 data groupswithin the corresponding burst section, thereby creating the RS frame.Herein, when it is assumed that the block decoder 1005 outputs a softdecision value for the decoding result, the RS frame decoder may decidethe ‘0’ and ‘1’ of the corresponding bit by using the codes of the softdecision value. 8 bits that are each decided as described above aregrouped to create one data byte. If the above-described process isperformed on all soft decision values of the 18 data groups included ina single burst, the RS frame having the size of (N+2)*(187+P) bytes maybe configured. Additionally, the present invention uses the softdecision value not only to configure the RS frame but also to configurea reliability map. Herein, the reliability map indicates the reliabilityof the corresponding data byte, which is configured by grouping 8 bits,wherein the 8 bits are decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and grouped to configure one databyte, is determined to be unreliable, the corresponding data byte ismarked on the reliability map as an unreliable data byte.

Herein, determining the reliability of one data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the one data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the one data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of (N+2)*(187+P)bytes, the reliability map is also configured to have the size of(N+2)*(187+P) bytes. FIG. 56( a′) and FIG. 56( b′) respectivelyillustrate the process steps of configuring the reliability mapaccording to the present invention.

At this point, the RS frame of FIG. 56( b) and the RS frame reliabilitymap of FIG. 56( b′) are interleaved in super frame units (as shown inFIG. 8). Therefore, the RS frame and the RS frame reliability maps aregrouped to create a super frame and a super frame reliability map.Subsequently, as shown in FIG. 56( c) and FIG. 56( c′), a de-permutation(or deinterleaving) process is performed in super frame units on the RSframe and the RS frame reliability maps, as an inverse process of thetransmitting system. Then, when the de-permutation process is performedin super frame units, the processed data are divided into de-permuted(or deinterleaved) RS frames having the size of (N+2)*(187+P) bytes andde-permuted RS frame reliability maps having the size of (N+2)*(187+P)bytes, as shown in FIG. 56( d) and FIG. 56( d′). Subsequently, the RSframe reliability map is used on the divided RS frames so as to performerror correction.

FIG. 57 illustrates example of the error correction processed accordingto embodiments of the present invention. FIG. 57 illustrates an exampleof performing an error correction process when the transmitting systemhas performed both RS encoding and CRC encoding processes on the RSframe. As shown in FIG. 57( a) and FIG. 57( a′), when the RS framehaving the size of (N+2)*(187+P) bytes and the RS frame reliability maphaving the size of (N+2)*(187+P) bytes are created, a CRC syndromechecking process is performed on the created RS frame, thereby verifyingwhether any error has occurred in each row. Subsequently, as shown inFIG. 57( b), a 2-byte checksum is removed to configure an RS framehaving the size of N*(187+P) bytes. Herein, the presence (or existence)of an error is indicated on an error flag corresponding to each row.Similarly, since the portion of the reliability map corresponding to theCRC checksum has hardly any applicability, this portion is removed sothat only N*(187+P) number of the reliability information bytes remain,as shown in FIG. 57( b′).

After performing the CRC syndrome checking process, as described above,a RS decoding process is performed in a column direction. Herein, a RSerasure correction process may be performed in accordance with thenumber of CRC error flags. More specifically, as shown in FIG. 57( c),the CRC error flag corresponding to each row within the RS frame isverified. Thereafter, the RS frame decoder 1006 determines whether thenumber of rows having a CRC error occurring therein is equal to orsmaller than the maximum number of errors on which the RS erasurecorrection may be performed, when performing the RS decoding process ina column direction. The maximum number of errors corresponds to P numberof parity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column (i.e., P=48).

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having (187+P) number of N-byte rows(i.e., 235 N-byte rows), as shown in FIG. 57( d). Thereafter, as shownin FIG. 57( e), the 48-byte parity data that have been added at the endof each column are removed. Conversely, however, if the number of rowshaving the CRC errors occurring therein is greater than the maximumnumber of errors (i.e., 48 errors) that can be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process. In addition, the reliability map, which hasbeen created based upon the soft decision value along with the RS frame,may be used to further enhance the error correction ability (orperformance) of the present invention.

More specifically, the RS frame decoder compares the absolute value ofthe soft decision value of the block decoder 1005 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, 8 bits, each being determined by the code of the softdecision value, are grouped to form one data byte. Accordingly, thereliability information on this one data byte is indicated on thereliability map. Therefore, as shown in FIG. 57( c), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method of the present invention, when it isdetermined that CRC errors are included in the corresponding row, basedupon the result of the CRC syndrome checking result, only the bytes thatare determined by the reliability map to be unreliable are set aserrors. More specifically, only the bytes corresponding to the row thatis determined to have errors included therein and being determined to beunreliable based upon the reliability information, are set as theerasure points. Thereafter, if the number of error points for eachcolumn is smaller than or equal to the maximum number of errors (i.e.,48 errors) that can be corrected by the RS erasure decoding process, anRS erasure decoding process is performed on the corresponding column.Conversely, if the number of error points for each column is greaterthan the maximum number of errors (i.e., 48 errors) that can becorrected by the RS erasure decoding process, a general decoding processis performed on the corresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as 50erasure points in the second column. In this case, a (235,187)-RSerasure decoding process is performed on the first column.Alternatively, a (235,187)-RS decoding process is performed on thesecond column. When error correction decoding is performed on all columndirections within the RS frame by using the above-described process, the48-byte parity data which were added at the end of each column areremoved, as shown in FIG. 57( e).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, while performing error correction decoding on theparticular column, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, RS erasure decoding may beperformed on the corresponding column. Herein, the difference betweenthe general RS decoding process and the RS erasure decoding process isthe number of errors that can be corrected.

More specifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 48 errors may be corrected).

After performing the error correction decoding process, as describedabove, a RS frame configured of 187 N-byte rows (or packet) may beobtained as shown in FIG. 57( e). The RS frame having the size of N*187bytes is outputted by the order of N number of 187-byte units. At thispoint, 1 MPEG synchronization byte, which had been removed by thetransmitting system, is added to each 187-byte packet, as shown in FIG.57( f). Therefore, a 188-byte unit mobile service data packet isoutputted. As described above, the RS frame decoded mobile service dataare outputted to the data derandomizer 1007. The data derandomizer 1007performs a derandomizing process, which corresponds to an inverseprocess of the randomizer included in the transmitting system, on theinputted mobile service data. Then, by outputting the derandomized data,the mobile service data transmitted from the transmitting system may beobtained.

General Digital Broadcast Receiving System

FIG. 58 illustrates a block diagram showing a structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Herein, the demodulating unit of FIG. 29 may be applied inthe digital broadcast receiving system. Referring to FIG. 58, thedigital broadcast receiving system includes a tuner 6001, a demodulatingunit 6002, a demultiplexer 6003, an audio decoder 6004, a video decoder6005, a native TV application manager 6006, a channel manager 6007, achannel map 6008, a first memory 6009, an SI and/or data decoder 6010, asecond memory 6011, a system manager 6012, a data broadcast applicationmanager 6013, a storage controller 6014, a third memory 6015, and a GPSmodule 6020. Herein, the first memory 6009 corresponds to a non-volatilerandom access memory (NVRAM) (or a flash memory). The third memory 6015corresponds to a large-scale storage device, such as a hard disk drive(HDD), a memory chip, and so on.

The tuner 6001 tunes a frequency of a specific channel through any oneof an antenna, cable, and satellite. Then, the tuner 6001 down-convertsthe tuned frequency to an intermediate frequency (IF), which is thenoutputted to the demodulating unit 6002. At this point, the tuner 6001is controlled by the channel manager 6007. Additionally, the result andstrength of the broadcast signal of the tuned channel are also reportedto the channel manager 6007. The data that are being received by thefrequency of the tuned specific channel include main service data,mobile service data, and table data for decoding the main service dataand mobile service data.

According to the embodiment of the present invention, audio data andvideo data for mobile broadcast programs may be applied as the mobileservice data. Such audio data and video data are compressed by varioustypes of encoders so as to be transmitted to a broadcasting station. Inthis case, the video decoder 6004 and the audio decoder 6005 will beprovided in the receiving system so as to correspond to each of theencoders used for the compression process. Thereafter, the decodingprocess will be performed by the video decoder 6004 and the audiodecoder 6005. Then, the processed video and audio data will be providedto the users. Examples of the encoding/decoding scheme for the audiodata may include AC 3, MPEG 2 AUDIO, MPEG 4 AUDIO, AAC, AAC+, HE AAC,AAC SBR, MPEG-Surround, and BSAC. And, examples of the encoding/decodingscheme for the video data may include MPEG 2 VIDEO, MPEG 4 VIDEO, H.264,SVC, and VC-1.

Depending upon the embodiment of the present invention, examples of themobile service data may include data provided for data service, such asJava application data, HTML application data, XML data, and so on. Thedata provided for such data services may correspond either to a Javaclass file for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the mobile service data may correspond to metadata. For example, the meta data be written in XML format so as to betransmitted through a DSM-CC protocol.

The demodulating unit 6002 performs VSB-demodulation and channelequalization on the signal being outputted from the tuner 6001, therebyidentifying the main service data and the mobile service data.Thereafter, the identified main service data and mobile service data areoutputted in TS packet units. An example of the demodulating unit 6002is shown in FIG. 29 to FIG. 57. Therefore, the structure and operationof the demodulator will be described in detail in a later process.However, this is merely exemplary and the scope of the present inventionis not limited to the example set forth herein. In the embodiment givenas an example of the present invention, only the mobile service datapacket outputted from the demodulating unit 6002 is inputted to thedemultiplexer 6003. In this case, the main service data packet isinputted to another demultiplexer (not shown) that processes mainservice data packets. Herein, the storage controller 6014 is alsoconnected to the other demultiplexer in order to store the main servicedata after processing the main service data packets. The demultiplexerof the present invention may also be designed to process both mobileservice data packets and main service data packets in a singledemultiplexer.

The storage controller 6014 is interfaced with the demultipelxer so asto control instant recording, reserved (or pre-programmed) recording,time shift, and so on of the mobile service data and/or main servicedata. For example, when one of instant recording, reserved (orpre-programmed) recording, and time shift is set and programmed in thereceiving system (or receiver) shown in FIG. 58, the correspondingmobile service data and/or main service data that are inputted to thedemultiplexer are stored in the third memory 6015 in accordance with thecontrol of the storage controller 6014. The third memory 6015 may bedescribed as a temporary storage area and/or a permanent storage area.Herein, the temporary storage area is used for the time shiftingfunction, and the permanent storage area is used for a permanent storageof data according to the user's choice (or decision).

When the data stored in the third memory 6015 need to be reproduced (orplayed), the storage controller 6014 reads the corresponding data storedin the third memory 6015 and outputs the read data to the correspondingdemultiplexer (e.g., the mobile service data are outputted to thedemultiplexer 6003 shown in FIG. 58). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 6015 is limited, the compression encoded mobile servicedata and/or main service data that are being inputted are directlystored in the third memory 6015 without any modification for theefficiency of the storage capacity. In this case, depending upon thereproduction (or reading) command, the data read from the third memory6015 pass trough the demultiplexer so as to be inputted to thecorresponding decoder, thereby being restored to the initial state.

The storage controller 6014 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 6015 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 6014compression encodes the inputted data and stored the compression-encodeddata to the third memory 6015. In order to do so, the storage controller6014 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 6014.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 6015, the storage controller6014 scrambles (or encrypts) the input data and stores the scrambled (orencrypted) data in the third memory 6015. Accordingly, the storagecontroller 6014 may include a scramble algorithm (or encryptionalgorithm) for scrambling the data stored in the third memory 6015 and adescramble algorithm (or decryption algorithm) for descrambling (ordecrypting) the data read from the third memory 6015. The scramblingmethod may include using an arbitrary key (e.g., control word) to modifya desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 6003 receives the real-time data outputtedfrom the demodulating unit 6002 or the data read from the third memory6015 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 6003 performs demultiplexing on themobile service data packet. Therefore, in the present invention, thereceiving and processing of the mobile service data will be described indetail. However, depending upon the many embodiments of the presentinvention, not only the mobile service data but also the main servicedata may be processed by the demultiplexer 6003, the audio decoder 6004,the video decoder 6005, the native TV application manager 6006, thechannel manager 6007, the channel map 6008, the first memory 6009, theSI and/or data decoder 6010, the second memory 6011, a system manager6012, the data broadcast application manager 6013, the storagecontroller 6014, the third memory 6015, and the GPS module 6020.Thereafter, the processed data may be used to provide diverse servicesto the users.

The demultiplexer 6003 demultiplexes mobile service data and systeminformation (SI) tables from the mobile service data packet inputted inaccordance with the control of the SI and/or data decoder 6010.Thereafter, the demultiplexed mobile service data and SI tables areoutputted to the SI and/or data decoder 6010 in a section format. Inthis case, it is preferable that data for the data service are used asthe mobile service data that are inputted to the SI and/or data decoder6010. In order to extract the mobile service data from the channelthrough which mobile service data are transmitted and to decode theextracted mobile service data, system information is required. Suchsystem information may also be referred to as service information. Thesystem information may include channel information, event information,etc. In the embodiment of the present invention, the PSI/PSIP tables areapplied as the system information. However, the present invention is notlimited to the example set forth herein. More specifically, regardlessof the name, any protocol transmitting system information in a tableformat may be applied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number.

FIG. 59 illustrates a VCT syntax according to an embodiment of thepresent invention. The VCT syntax of FIG. 59 is configured by includingat least one of a table_id field, a section_syntax_indicator field, aprivate_indicator field, a section_length field, a transport_stream idfield, a version_number field, a current_next_indicator field, asection_number field, a last_section_number field, a protocol_versionfield, and a num_channels_in_section field.

The VCT syntax further includes a first ‘for’ loop repetition statementthat is repeated as much as the num_channels_in_section field value. Thefirst repetition statement may include at least one of a short_namefield, a major_channel_number field, a minor_channel_number field, amodulation_mode field, a carrier_frequency field, a channel_TSID field,a program_number field, an ETM_location field, an access_controlledfield, a hidden field, a service_type field, a source_id field, adescriptor_length field, and a second ‘for’ loop statement that isrepeated as much as the number of descriptors included in the firstrepetition statement. Herein, the second repetition statement will bereferred to as a first descriptor loop for simplicity. The descriptordescriptors( ) included in the first descriptor loop is separatelyapplied to each virtual channel.

Furthermore, the VCT syntax may further include anadditional_descriptor_length field, and a third ‘for’ loop statementthat is repeated as much as the number of descriptors additionally addedto the VCT. For simplicity of the description of the present invention,the third repetition statement will be referred to as a seconddescriptor loop. The descriptor additional_descriptors( ) included inthe second descriptor loop is commonly applied to all virtual channelsdescribed in the VCT.

As described above, referring to FIG. 59, the table_id field indicates aunique identifier (or identification) (ID) that can identify theinformation being transmitted to the table as the VCT. Morespecifically, the table_id field indicates a value informing that thetable corresponding to this section is a VCT. For example, a 0xC8 valuemay be given to the table_id field.

The version_number field indicates the version number of the VCT. Thesection_number field indicates the number of this section. Thelast_section_number field indicates the number of the last section of acomplete VCT. And, the num_channel_in_section field designates thenumber of the overall virtual channel existing within the VCT section.Furthermore, in the first ‘for’ loop repetition statement, theshort_name field indicates the name of a virtual channel. Themajor_channel_number field indicates a ‘major’ channel number associatedwith the virtual channel defined within the first repetition statement,and the minor_channel_number field indicates a ‘minor’ channel number.More specifically, each of the channel numbers should be connected tothe major and minor channel numbers, and the major and minor channelnumbers are used as user reference numbers for the corresponding virtualchannel.

The program_number field is shown for connecting the virtual channelhaving an MPEG-2 program association table (PAT) and program map table(PMT) defined therein, and the program_number field matches the programnumber within the PAT/PMT. Herein, the PAT describes the elements of aprogram corresponding to each program number, and the PAT indicates thePID of a transport packet transmitting the PMT. The PMT describedsubordinate information, and a PID list of the transport packet throughwhich a program identification number and a separate bit sequence, suchas video and/or audio data configuring the program, are beingtransmitted.

FIG. 60 illustrates a service_type field according to an embodiment ofthe present invention. The service_type field indicates the service_typeprovided in a corresponding virtual channel. Referring to FIG. 60, it isprovided that the service_type field should only indicate an analogtelevision, a digital television, digital audio data, and digital videodata. Also, according to the embodiment of the present invention, it maybe provided that a mobile broadcast program should be designated to theservice_type field. The service_type field, which is parsed by the SIand/or data decoder 6010 may be provided to a receiving system, as shownin FIG. 58, and used accordingly. According to other embodiments of thepresent invention, the parsed service_type field may also be provided toeach of the audio decoder 6004 and video decoder 6005, so as to be usedin the decoding process.

The source_id field indicates a program source connected to thecorresponding virtual channel. Herein, a source refers to a specificsource, such as an image, a text, video data, or sound. The source_idfield value has a unique value within the transport stream transmittingthe VCT. Meanwhile, a service location descriptor may be included in adescriptor loop (i.e., descriptor{ }) within a next ‘for’ looprepetition statement. The service location descriptor may include astream type, PID, and language code for each elementary stream.

FIG. 61 illustrates a service location descriptor according to anembodiment of the present invention. As shown in FIG. 61, the servicelocation descriptor may include a descriptor_tag field, adescriptor_length field, and a PCR_PID field. Herein, the PCR_PID fieldindicates the PID of a transport stream packet within a programspecified by a program_number field, wherein the transport stream packetincludes a valid PCR field. Meanwhile, the service location descriptorincludes a number_elements field so as to indicate a number of PIDs usedin the corresponding program. The number of repetition of a next ‘for’descriptor loop repetition statement can be decided, depending upon thevalue of the number_elements field. Referring to FIG. 61, the ‘for’ looprepetition statement includes a stream_type field, an elementary_PIDfield, and an ISO_(—)639_language_code field. Herein, the stream_typefield indicates the stream type of the corresponding elementary stream(i.e., video/audio data). The elementary_PID field indicates the PID ofthe corresponding elementary stream. The ISO_(—)639_language_code fieldindicates a language code of the corresponding elementary stream.

FIG. 62 illustrates examples that may be assigned to the stream_typefield according to the present invention. As shown in FIG. 62, ISO/IEC11172 Video, ITU-T Rec. H.262|ISO/IEC 13818-2 Video or ISO/IEC 11172-2constrained parameter video stream, ISO/IEC 11172 Audio, ISO/IEC 13818-3Audio, ITU-T Rec. H.222.0|ISO/IEC 13818-1 private_sections, ITU-T Rec.H.222.0|ISO/IEC 13818-1 PES packets containing private data, ISO/IEC13522 MHEG, ITU-T Rec. H.222.0|ISO/IEC 13818-1 Annex A DSM CC, ITU-TRec. H.222.1, ISO/IEC 13818-6 type A, ISO/IEC 13818-6 type B, ISO/IEC13818-6 type C, ISO/IEC 13818-6 type D, ISO/IEC 13818-1 auxiliary, andso on may be applied as the stream type. Meanwhile, according to theembodiment of the present invention, MPH video stream: Non-hierarchicalmode, MPH audio stream: Non-hierarchical mode, MPH Non-A/V stream:Non-hierarchical mode, MPH High Priority video stream: Hierarchicalmode, MPH High Priority audio stream: Hierarchical mode, MPH LowPriority video stream: Hierarchical mode, MPH Low priority audio stream:Hierarchical mode, and so on may further be applied as the stream type.

As described above, “MPH” corresponds to the initials of “mobile”,“pedestrian”, and “handheld” and represents the opposite concept of afixed-type system. Therefore, the MPH video stream: Non-hierarchicalmode, the MPH audio stream: Non-hierarchical mode, the MPH Non-A/Vstream Non-hierarchical mode, the MPH High Priority video streamHierarchical mode, the MPH High Priority audio stream Hierarchical mode,the MPH Low Priority video stream Hierarchical mode, and the MPH Lowpriority audio stream Hierarchical mode correspond to stream types thatare applied when mobile broadcast programs are being transmitted andreceived. Also the Hierarchical mode and the Non-hierarchical mode eachcorrespond to values that are used in stream types having differentpriority levels. Herein, the priority level is determined based upon ahierarchical structure applied in any one of the encoding or decodingmethod.

Therefore, when a hierarchical structure-type codec is used, a fieldvalue including the hierarchical mode and the non-hierarchical mode isrespectively designated so as to identify each stream. Such stream typeinformation is parsed by the SI and/or data decoder 6010, so as to beprovided to the video and audio decoders 6004 and 6005. Thereafter, eachof the video and audio decoders 6004 and 6005 uses the parsed streamtype information in order to perform the decoding process. Other streamtypes that may be applied in the present invention may include MPEG 4AUDIO, AC 3, AAC, AAC+, BSAC, HE AAC, AAC SBR, and MPEG-S for the audiodata, and may also include MPEG 2 VIDEO, MPEG 4 VIDEO, H.264, SVC, andVC-1 for the video data.

Furthermore, referring to FIG. 62, in fields using the hierarchical modeand the non-hierarchical mode, such as the MPH video stream:Non-hierarchical mode and the MPH audio stream: Non-hierarchical mode,examples of using the MPEG 4 AUDIO, AC 3, AAC, AAC+, BSAC, HE AAC, AACSBR, and MPEG-S for the audio data, and the MPEG 2 VIDEO, MPEG 4 VIDEO,H.264, SVC, and VC-1 for the video data may also be respectively used asreplacements for each of the audio stream and the video stream may beconsidered as other embodiments of the present invention and may,therefore, be included in the scope of the present invention. Meanwhile,the stream_type field may be provided as one of the fields within thePMT. And, in this case, it is apparent that such stream_type fieldincludes the above-described syntax. The STT transmits information onthe current data and timing information. The RRT transmits informationon region and consultation organs for program ratings. The ETT transmitsadditional description of a specific channel and broadcast program. TheEIT transmits information on virtual channel events (e.g., programtitle, program start time, etc.).

FIG. 63 illustrates a bit stream syntax for an event information table(EIT) according to the present invention. In this embodiment, the EITshown in FIG. 63 corresponds to a PSIP table including information on atitle, start time, duration, and so on of an event in a virtual channel.Referring to FIG. 63, the EIT is configured of a plurality of fieldsincluding a table_id field, a section_syntax_indicator field, aprivate_indicator field, a source_ID, a version_numbers_in_sectionfield, a current_next_indicator field, and a num_event field. Morespecifically, the table_id field is an 8-bit field having the value of‘oxCB’, which indicates that the corresponding section is included inthe EIT. The section_syntax_indicator field is a 1-bit field having thevalue of ‘1’. This indicates that the corresponding section passesthrough the section_length field and is in accordance with a genericsection syntax. The private_indicator field corresponds to a 1-bit fieldhaving the value of ‘1’.

Also, the source_ID corresponds to an ID identifying a virtual channelthat carries an event shown in the above-described table. Theversion_numbers_in_section field indicates the version of an elementincluded in the event information table. In the present invention, withrespect to the previous version number, an event change informationincluded in the event information table, wherein the event changeinformation has a new version number is recognized as the latest changein information. The current_next_indicator field indicates whether theevent information included in the corresponding EIT is a currentinformation or a next information. And, finally, the num_event fieldrepresents the number of events included in the channel having a sourceID. More specifically, an event loop shown below is repeated as manytimes as the number of events.

The above-described EIT field is commonly applied to at least one ormore events included in one EIT syntax. A loop statement, which isincluded as “for (j=0;j<num_event_in_section;j++){ }”, describes thecharacteristics of each event. The following fields represent detailedinformation of each individual event. Therefore, the following fieldsare individually applied to each corresponding event described by theEIT syntax. An event_ID included in an event loop is an identifier foridentifying each individual event. The number of the event IDcorresponds to a portion of the identifier for even extended textmessage (i.e., ETM_ID). A start_time field indicates the starting timeof an event. Therefore, the start_time field collects the starting timeinformation of a program provided from an electronic programinformation. A length_in_seconds field indicates the duration of anevent. Therefore, the length_in_seconds field collects the ending timeinformation of a program provided from an electronic programinformation. More specifically, the ending time information is collectedby adding the start_time field value and the length_in_secodns fieldvalue. A title_text( ) field may be used to indicate the tile of abroadcast program.

Meanwhile, the descriptor applied to each event may be included in theEIT. Herein, a descriptors_length field indicates the length of adescriptor. Also, a descriptor loop (i.e., descriptor{ }) included in a‘for’ loop repetition statement includes at least one of an AC-3 audiodescriptor, an MPEG 2 audio descriptor, an MPEG 4 audio descriptor, anAAC descriptor, an AAC+descriptor, an HE AAC descriptor, an AAC SBRdescriptor, an MPEG surround descriptor, a BSAC descriptor, an MPEG 2video descriptor, an MPEG 4 video descriptor, an H.264 descriptor, anSVC descriptor, and a VC-1 descriptor. Herein, each descriptor describesinformation on audio/video codec applied to each event. Such codecinformation may be provided to the audio/video decoder 6004 and 6005 andused in the decoding process.

Finally, the DCCT/DCCSCT transmits information associated with automatic(or direct) channel change. And, the MGT transmits the versions and PIDinformation of the above-mentioned tables included in the PSIP. Each ofthe above-described tables included in the PSI/PSIP is configured of abasic unit referred to as a “section”, and a combination of one or moresections forms a table. For example, the VCT may be divided into 256sections. Herein, one section may include a plurality of virtual channelinformation. However, a single set of virtual channel information is notdivided into two or more sections. At this point, the receiving systemmay parse and decode the data for the data service that are transmittingby using only the tables included in the PSI, or only the tablesincluded in the PSIP, or a combination of tables included in both thePSI and the PSIP. In order to parse and decode the mobile service data,at least one of the PAT and PMT included in the PSI, and the VCTincluded in the PSIP is required. For example, the PAT may include thesystem information for transmitting the mobile service data, and the PIDof the PMT corresponding to the mobile service data (or program number).The PMT may include the PID of the TS packet used for transmitting themobile service data. The VCT may include information on the virtualchannel for transmitting the mobile service data, and the PID of the TSpacket for transmitting the mobile service data.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up. The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective SI tables (i.e., a bouquet associate table(BAT), a running status table (RST), and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRD to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, when the mobile service data correspond toaudio data and video data, it is preferable that the mobile service dataincluded (or loaded) in a payload within a TS packet correspond to PEStype mobile service data. According to another embodiment of the presentinvention, when the mobile service data correspond to the data for thedata service (or data service data), the mobile service data included inthe payload within the TS packet consist of a digital storagemedia-command and control (DSM-CC) section format. However, the TSpacket including the data service data may correspond either to apacketized elementary stream (PES) type or to a section type. Morespecifically, either the PES type data service data configure the TSpacket, or the section type data service data configure the TS packet.The TS packet configured of the section type data will be given as theexample of the present invention. At this point, the data service dataare includes in the digital storage media-command and control (DSM-CC)section. Herein, the DSM-CC section is then configured of a 188-byteunit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge the reception of the databroadcast program including mobile service data. At this point, themobile service data may be transmitted by a data/object carousel method.The data/object carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the SI and/or data decoder6010, the demultiplexer 6003 performs section filtering, therebydiscarding repetitive sections and outputting only the non-repetitivesections to the SI and/or data decoder 6010. The demultiplexer 6003 mayalso output only the sections configuring desired tables (e.g., VCT orEIT) to the SI and/or data decoder 6010 by section filtering. Herein,the VCT or EIT may include a specific descriptor for the mobile servicedata. However, the present invention does not exclude the possibilitiesof the mobile service data being included in other tables, such as thePMT. The section filtering method may include a method of verifying thePID of a table defined by the MGT, such as the VCT, prior to performingthe section filtering process. Alternatively, the section filteringmethod may also include a method of directly performing the sectionfiltering process without verifying the MGT, when the VCT includes afixed PID (i.e., a base PID). At this point, the demultiplexer 6003performs the section filtering process by referring to a table_id field,a version_number field, a section_number field, etc. As described above,the method of defining the PID of the VCT broadly includes two differentmethods. Herein, the PID of the VCT is a packet identifier required foridentifying the VCT from other tables. The first method consists ofsetting the PID of the VCT so that it is dependent to the MGT. In thiscase, the receiving system cannot directly verify the VCT among the manyPSI and/or PSIP tables. Instead, the receiving system must check the PIDdefined in the MGT in order to read the VCT. Herein, the MGT defines thePID, size, version number, and so on, of diverse tables. The secondmethod consists of setting the PID of the VCT so that the PID is given abase PID value (or a fixed PID value), thereby being independent fromthe MGT. In this case, unlike in the first method, the VCT according tothe present invention may be identified without having to verify everysingle PID included in the MGT. Evidently, an agreement on the base PIDmust be previously made between the transmitting system and thereceiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer6003 may output only an application information table (AIT) to the SIand/or data decoder 6010 by section filtering. The AIT includesinformation on an application being operated in the receiver for thedata service. The AIT may also be referred to as an XAIT, and an AMT.Therefore, any table including application information may correspond tothe following description. When the AIT is transmitted, a value of‘0x05’ may be assigned to a stream_type field of the PMT. The AIT mayinclude application information, such as application name, applicationversion, application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_network_id field, the transport_stream id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 6011 by the SI and/or data decoder 6010.

The SI and/or data decoder 6010 parses the DSM-CC section configuringthe demultiplexed mobile service data. Then, the mobile service datacorresponding to the parsed result are stored as a database in thesecond memory 6011. The SI and/or data decoder 6010 groups a pluralityof sections having the same table identification (table_id) so as toconfigure a table, which is then parsed. Thereafter, the parsed resultis stored as a database in the second memory 6011. At this point, byparsing data and/or sections, the SI and/or data decoder 6010 reads allof the remaining actual section data that are not section-filtered bythe demultiplexer 6003. Then, the SI and/or data decoder 6010 stores theread data to the second memory 6011. The second memory 6011 correspondsto a table and data/object carousel database storing system informationparsed from tables and mobile service data parsed from the DSM-CCsection. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT. When the VCT isparsed, information on the virtual channel to which mobile service dataare transmitted may be obtained.

Also, according to the present invention, the SI and/or data decoder6010 parses the SLD of the VCT, thereby transmitting the stream typeinformation of the corresponding elementary stream to the audio decoder6004 or the video decoder 6005. In this case, the corresponding audiodecoder 6004 or video decoder 6005 uses the transmitted stream typeinformation so as to perform the audio or video decoding process.Furthermore, according to the present invention, the SI and/or datadecoder 6010 parses an AC-3 audio descriptor, an MPEG 2 audiodescriptor, an MPEG 4 audio descriptor, an AAC descriptor, anAAC+descriptor, an HE AAC descriptor, an AAC SBR descriptor, an MPEGsurround descriptor, a BSAC descriptor, an MPEG 2 video descriptor, anMPEG 4 video descriptor, an H.264 descriptor, an SVC descriptor, a VC-1descriptor, and so on, of the EIT, thereby transmitting the audio orvideo codec information of the corresponding event to the audio decoder6004 or video decoder 6005. In this case, the corresponding audiodecoder 6004 or video decoder 6005 uses the transmitted audio or videocodec information in order to perform an audio or video decodingprocess.

The obtained application identification information, service componentidentification information, and service information corresponding to thedata service may either be stored in the second memory 6011 or beoutputted to the data broadcasting application manager 6013. Inaddition, reference may be made to the application identificationinformation, service component identification information, and serviceinformation in order to decode the data service data. Alternatively,such information may also prepare the operation of the applicationprogram for the data service. Furthermore, the SI and/or data decoder6010 controls the demultiplexing of the system information table, whichcorresponds to the information table associated with the channel andevents. Thereafter, an A/V PID list may be transmitted to the channelmanager 6007.

The channel manager 6007 may refer to the channel map 6008 in order totransmit a request for receiving system-related information data to theSI and/or data decoder 6010, thereby receiving the corresponding result.In addition, the channel manager 6007 may also control the channeltuning of the tuner 6001. Furthermore, the channel manager 6007 maydirectly control the demultiplexer 6003, so as to set up the A/V PID,thereby controlling the audio decoder 6004 and the video decoder 6005.

The audio decoder 6004 and the video decoder 6005 may respectivelydecode and output the audio data and video data demultiplexed from themain service data packet. Alternatively, the audio decoder 6004 and thevideo decoder 6005 may respectively decode and output the audio data andvideo data demultiplexed from the mobile service data packet. Meanwhile,when the mobile service data include data service data, and also audiodata and video data, it is apparent that the audio data and video datademultiplexed by the demultiplexer 6003 are respectively decoded by theaudio decoder 6004 and the video decoder 6005. For example, anaudio-coding (AC)-3 decoding algorithm, an MPEG-2 audio decodingalgorithm, an MPEG-4 audio decoding algorithm, an AAC decodingalgorithm, an AAC+decoding algorithm, an HE AAC decoding algorithm, anAAC SBR decoding algorithm, an MPEG surround decoding algorithm, and aBSAC decoding algorithm may be applied to the audio decoder 6004. Also,an MPEG-2 video decoding algorithm, an MPEG-4 video decoding algorithm,an H.264 decoding algorithm, an SVC decoding algorithm, and a VC-1decoding algorithm may be applied to the video decoder 6005.Accordingly, the decoding process may be performed.

Meanwhile, the native TV application manager 6006 operates a nativeapplication program stored in the first memory 6009, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 6006 displays the user request on a screenthrough a graphic user interface (GUI), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 6006 and the databroadcasting application manager 6013. Furthermore, the native TVapplication manager 6006 controls the channel manager 6007, therebycontrolling channel-associated operations, such as the management of thechannel map 6008, and controlling the SI and/or data decoder 6010. Thenative TV application manager 6006 also controls the GUI of the overallreceiving system, thereby storing the user request and status of thereceiving system in the first memory 6009 and restoring the storedinformation.

The channel manager 6007 controls the tuner 6001 and the SI and/or datadecoder 6010, so as to managing the channel map 6008 so that it canrespond to the channel request made by the user. More specifically,channel manager 6007 sends a request to the SI and/or data decoder 6010so that the tables associated with the channels that are to be tuned areparsed. The results of the parsed tables are reported to the channelmanager 6007 by the SI and/or data decoder 6010. Thereafter, based onthe parsed results, the channel manager 6007 updates the channel map6008 and sets up a PID in the demultiplexer 6003 for demultiplexing thetables associated with the data service data from the mobile servicedata.

The system manager 6012 controls the booting of the receiving system byturning the power on or off. Then, the system manager 6012 stores ROMimages (including downloaded software images) in the first memory 6009.More specifically, the first memory 6009 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 6011 so as to provide the user with the dataservice. If the data service data are stored in the second memory 6011,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 6009 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stored managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied, the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory6009 upon the shipping of the receiving system, or be stored in thefirst memory 6009 after being downloaded. The application program forthe data service (i.e., the data service providing application program)stored in the first memory 6009 may also be deleted, updated, andcorrected. Furthermore, the data service providing application programmay be downloaded and executed along with the data service data eachtime the data service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 6013 operates thecorresponding application program stored in the first memory 6009 so asto process the requested data, thereby providing the user with therequested data service. And, in order to provide such data service, thedata broadcasting application manager 6013 supports the graphic userinterface (GUI). Herein, the data service may be provided in the form oftext (or short message service (SMS)), voice message, still image, andmoving image. The data broadcasting application manager 6013 may beprovided with a platform for executing the application program stored inthe first memory 6009. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 6013 executing the data serviceproviding application program stored in the first memory 6009, so as toprocess the data service data stored in the second memory 6011, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiver that is not equipped with an electronic mapand/or a GPS system in the form of at least one of a text (or shortmessage service (SMS)), a voice message, a graphic message, a stillimage, and a moving image. In this case, when a GPS module 6020 ismounted on the receiving system, as shown in FIG. 58, the GPS module6020 receives satellite signals transmitted from a plurality of lowearth orbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager6013.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 6011, the first memory 6009, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 6013, the dataservice data stored in the second memory 6011 are read and inputted tothe data broadcasting application manager 6013. The data broadcastingapplication manager 6013 translates (or deciphers) the data service dataread from the second memory 6011, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal. In other words, the data broadcasting application manager 6013uses the current position information and the graphic information, sothat the current position information can be processed and provided tothe user in a graphic format.

FIG. 64 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 64, the digitalbroadcast receiving system includes a tuner 7001, a demodulating unit7002, a demultiplexer 7003, a first descrambler 7004, an audio decoder7005, a video decoder 7006, a second descrambler 7007, an authenticationunit 7008, a native TV application manager 7009, a channel manager 7010,a channel map 7011, a first memory 7012, a data decoder 7013, a secondmemory 7014, a system manager 7015, a data broadcasting applicationmanager 7016, a storage controller 7017, a third memory 7018, atelecommunication module 7019, and a GPS module 7020. Herein, the thirdmemory 7018 is a mass storage device, such as a hard disk drive (HDD) ora memory chip. Also, during the description of the digital broadcast (ortelevision or DTV) receiving system shown in FIG. 64, the componentsthat are identical to those of the digital broadcast receiving system ofFIG. 58 will be omitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descramble the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an authentication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 7004 and 7007, and the authentication means will bereferred to as an authentication unit 7008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.64 illustrates an example of the descramblers 7004 and 7007 and theauthentication unit 7008 being provided inside the receiving system,each of the descramblers 7004 and 7007 and the authentication unit 7008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 7008, the scrambled broadcastingcontents are descrambled by the descramblers 7004 and 7007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 7008 and thedescramblers 7004 and 7007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 7001 and the demodulating unit 7002. Then, the system manager7015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 7002 may be included as ademodulating means according to embodiment of the present invention asdescribed in FIG. 29 to FIG. 57. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 7015 decides that the received broadcasting contentshave been scrambled, then the system manager 7015 controls the system tooperate the authentication unit 7008. As described above, theauthentication unit 7008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 7008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 7008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advance, with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 7008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 7008 determines that the two types ofinformation conform to one another, then the authentication unit 7008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or antherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem-specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 7008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 7008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 7008 determines that the information conform to eachother, then the authentication unit 7008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 7008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the above-mentioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 7015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 7015 transmits thepayment information to the remote transmitting system through thetelecommunication module 7019.

The authentication unit 7008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 7008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 7008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 7008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 7004 and 7007. Herein,the first and second descramblers 7004 and 7007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 7004 and 7007, so as to perform the descrambling process.More specifically, the first and second descramblers 7004 and 7007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 7004 and 7007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 7004 and 7007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 7004 and 7007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 7015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 7012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 7008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 7008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 7015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 7012 upon the shipping of the presentinvention, or be downloaded to the first memory 7012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 7016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 7003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 7004 and 7007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 7004 and7007. Each of the descramblers 7004 and 7007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 7004 and 7007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 7018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced). Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 7017, the storage controller 7017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 7018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associated with theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 7019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 7019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information). Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 7019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module7019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1×EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile internet,WiBro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 7019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 7003 receives either the real-time data outputted from thedemodulating unit 7002 or the data read from the third memory 7018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 7003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 7004 receives the demultiplexed signals from thedemultiplexer 7003 and then descrambles the received signals. At thispoint, the first descrambler 7004 may receive the authentication resultreceived from the authentication unit 7008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 7005 and the video decoder 7006 receive the signalsdescrambled by the first descrambler 7004, which are then decoded andoutputted. Alternatively, if the first descrambler 7004 did not performthe descrambling process, then the audio decoder 7005 and the videodecoder 7006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 7007 and processed accordingly.

As described above, the digital broadcasting system and data processingmethod according to the present invention have the following advantages.More specifically, the digital broadcasting system and data processingmethod according to the present invention is robust against (orresistant to) any error that may occur when transmitting mobile servicedata through a channel. And, the present invention is also highlycompatible to the conventional system. Moreover, the present inventionmay also receive the mobile service data without any error even inchannels having severe ghost effect and noise.

By inserting known data in specific positions (or places) within a dataregion, the present invention may enhance the receiving performance ofthe receiving system in an environment undergoing frequent channelchanges.

Finally, the present invention is even more effective when applied tomobile and portable receivers, which are also liable to a frequentchange in channel and which require protection (or resistance) againstintense noise.

1. A receiving system comprising: a receiving unit for receiving abroadcast signal including mobile service data and main service data,the mobile service data configuring a RS frame, the RS frame includingat least one data packet for the mobile service data, RS paritygenerated based on the at least one data packet, and CRC checksumgenerated based on the at least one data packet and the RS parity; ademodulator for converting RS frame data included in the broadcastsignal received by the receiving unit into a baseband RS frame data; anequalizer for performing channel equalization on the data demodulated bythe demodulator; a block decoder for performing symbol-decoding on thedata channel-equalized by the equalizer in block units; and a RS framedecoder for performing CRC-decoding and RS-decoding on the decodedmobile service data in RS frame units, thereby correcting errorsoccurred in the mobile service data within the RS frame.
 2. Thereceiving system of claim 1, wherein a data group configures a RS frame,wherein N number of known data sequences are inserted in some regionsamong a plurality of regions within the data group, and wherein atransmission parameter is inserted between a first known data sequenceand a second known data sequence, among the N number of known datasequences.
 3. The receiving system of claim 2, further comprising: atransmission parameter detector for detecting the transmissionparameter; and a power controller for controlling power based upon thedetected transmission parameter, thereby receiving a slot which a datagroup including requested mobile service data is assigned.
 4. Thereceiving system of claim 2, further comprising: a known sequencedetector for detecting the known data, wherein the equalizerchannel-equalizes the mobile service data using the detected known data.5. The receiving system of claim 2, wherein one RS frame data isassigned to at least some regions among a plurality of data group, thedata group configuring a plurality of regions, and then the assigned RSframe data is received.
 6. The receiving system of claim 2, wherein oneRS frame data among a plurality of RS frame is assigned to some regionsamong a plurality of data group, the data group configuring a pluralityof regions, and the other RS frame data is assigned to the remainingregions within the corresponding data group, and then the assigned RSframe data is received.
 7. The receiving system of claim 2, wherein themultiplexing rule of the data group determines by the followingEquation.SLOT_(i)=((4(i−1)+0_(i)) mod 16)+1 Herein, 0_(i)=0 if 0≦i≦4, 0_(i)=2else if i≦8, 0_(i)=1 else if i≦12, 0_(i)=3 else. Herein, 1≦SLOT_(i)≦16,and 1≦i≦TNOG. SLOT_(i) indicates a slot being assigned with an i^(th)data group within a sub-frame, TNOG represents a total number of datagroups assigned to one sub-frame.
 8. A method for processing data in areceiving system, comprising: receiving a broadcast signal includingmobile service data and main service data, the mobile service dataconfiguring a RS frame, the RS frame including at least one data packetfor the mobile service data, RS parity generated based on the at leastone data packet, and CRC checksum generated based on the at least onedata packet and the RS parity; converting RS frame data included in thereceived broadcast signal into a baseband RS frame data; performingchannel equalization on the demodulated data; performing symbol-decodingon the channel-equalized data in block units; and performingCRC-decoding and RS-decoding on the decoded mobile service data in RSframe units, thereby correcting errors occurred in the mobile servicedata within the RS frame.
 9. The method of claim 8, wherein a data groupconfigures a RS frame, wherein N number of known data sequences areinserted in some regions among a plurality of regions within the datagroup, and wherein a transmission parameter is inserted between a firstknown data sequence and a second known data sequence, among the N numberof known data sequences.
 10. The method of claim 9, further comprising:detecting the transmission parameter; and controlling power based uponthe detected transmission parameter, thereby receiving a slot which adata group including requested mobile service data is assigned.
 11. Themethod of claim 9, further comprising: detecting the known data, whereinthe equalizing step channel-equalizes the mobile service data using thedetected known data.
 12. The method of claim 9, wherein one RS framedata is assigned to at least some regions among a plurality of datagroup, the data group configuring a plurality of regions, and then theassigned RS frame data is received.
 13. The method of claim 9, whereinone RS frame data among a plurality of RS frame is assigned to someregions among a plurality of data group, the data group configuring aplurality of regions, and the other RS frame data is assigned to theremaining regions within the corresponding data group, and then theassigned RS frame data is received.
 14. The method of claim 9, wherein amultiplexing rule of the data group determines based upon the followingEquation.SLOT_(i)=((4(i−1)+0_(i)) mod 16)+1 Herein, 0_(i)=0 if 1≦i≦4, 0_(i)=2else if i≦8, 0_(i)=1 else if i≦12, 0_(i)=3 else. Herein, 1≦SLOT_(i)≦16,and 1≦i≦TNOG. SLOT_(i) indicates a slot being assigned with an i^(th)data group within a sub-frame, TNOG represents a total number of datagroups assigned to one sub-frame.